"Ejaculation" is the first episode of the first season of Big Mouth. It is the first episode of the series overall. It premiered on September 29, 2017. It was written by Nick Kroll and directed by Joel Moser.
As Andrew falls under the spell of the randy Hormone Monster, his buddy Nick becomes obsessed with the lack of changes in his own body.
The episode opens at Bridgeton Middle School, with the seventh-grade class watching a video on the female reproductive organs. Nick and Andrew are confused at the news of females having uteruses, thinking that "vagina" is a slang term. When Andrew says the word vagina Maury, his hormone monster, pops out of his desk and torments him, by descriptively describing the female productive system until he gets an erection. Annoyed, Andrew tries to deny his hormone monster's existence, by telling him that he's nothing more than a fictional character that his brain created. However, he still gets a boner and leaves the class, knowing that he has to jerk off in order for Maury to leave him alone. Meanwhile, Jessi claims it's easier for boys to go through puberty, comparing a pubescent female to "a yarn ball of aching tubes" and superfluously adds that girls need equal pay. Jay argues back, saying that when maternity leave is factored in then women do get equal pay. Jessi points out that he's just quoting his dad's law commercial and also calls his father a "scumbag DUI attorney". Matthew gets in on the conversation and makes a dig at Jay for having a unibrow. As Andrew rushes eave the room, Missy, concerned for his well-being tells him that she'll take notes for him, so he won't miss anything.
After school, Nick has Andrew come over to his house for a sleepover. At the dinner table, Nick's parents, Elliot and Diane talk about how much they love their children, including Nick's older sister and brother, Leah and Judd. They also say that Andrew is so close to Nick, that they consider him to be an unofficial "fourth child" of theirs. Elliot tells Andrew an interesting fun fact about their house, saying that famous jazz musician, Duke Ellington used to live there and that according to urban legend, his ghost still resigns in the house's attic.
In Nick's bedroom, Andrew tells him that he's not going to go to the upcoming dance on Friday, as he doesn't want to ask out a girl and get inevitable rejected. Nick says that he doesn't need to get a date. The plans for the dance are for Nick, Andrew, Jessi, and Jay to go as a group of friends. Andrew brings up how Jay once told him that he's going to get "fingered" at the dance. Confused and mildly disgusted, Nick believed that Andrew is misquoting Jay. Both boys doubt that Jay has even kissed a girl, let along with tongue. They both believe that you need to use major tongue, in order to make a kiss official.
When Andrew is finished in the bathroom he walks into Nick's room wearing a towel. Nick jumps out of a cupboard to scare him as a joke. Frightened, Andrew drops his towel, exposing his penis to Nick. Nick can't help but glance down at Andrew's dick and stare at it, even though it's disgusting for him and embarrassing for his Andrew. Nick notices that Andrew's dick is significantly bigger and hairier than his before the latter finally runs back into the bathroom again.
That night, both boys are laying in bed with their eyes wide open, still shocked by the incident. Nick told Andrew he didn't even look, which was a total lie. Andrew responds that he doesn't even know what he's talking about, which was also a total lie. After an awkward couple of hours later, Nick goes to sleep, while Andrew still stays awake. Maury comes to visit again and tells Andrew to masturbate. Andrew refused to do so while laying next to his friend, but Maury tells him that it's perfectly normal. Maury finally persuades Andrew to jack off to the cat clock on Nick's wall and imagine it as his dad's associate Susan.
The next morning Nick's parents drop Andrew off at his house on Sunday. Nick's parents suspect something is up, as the initial plans for Nick and Andrew's sleepover were for Andrew to stay over the entire weekend. Nick tells them that he saw Andrew's penis the night prior, and he feels inferior, due to Andrew's dick being bigger than his. Diane explains that Andrew has just hit puberty and assures him that he'll be going through the same changes soon. Nick still feels as though the change isn't happening soon enough and starts feeling back that he's not growing or getting any pubic hair.
The next coming Monday, Nick is in the locker room with Andrew and the other boys. Coach Steve announces again that the dance is coming up and that he'll be supervising them there. While he does this, Nick notices Andrew's bulge and starts hallucinating the other boys as giant penises. This continues on during the basketball game and when one of the dicks approaches him, Nick freaks out and pushes it away. The imagination sequence ends, revealing that he just pushed his own friend Andrew to the ground for no reason. Andrew looks at Nick funny and asks what's up. Nick just stands there nervously and doesn't respond. The other kids stop to stare at them until Coach Steve finally breaks everything up and tells them to get back to the game. He, himself, jumps up to dunk a basketball, only to drop to the ground and knock the wind out of his balls.
That night at home, Andrew paces his bedroom floor, pondering why Nick is acting so weird, while his hormone monster sits on his bed and listens. Andrew worries that Nick may have heard him jerking off and now he resents him for it. Maury suggests that maybe he's just jealous of how much bigger his dick is and prompts him to kick his ass but Andrew refuses to treat his own friend that way.
Meanwhile, at The Birch House, Nick goes to the attic to meet with The Ghost of Duke Ellington, seeking emotional support from him. The Ghost of Duke Ellington comes up and tells him that back in 1938, he saw Charlie Parker's penis at a nightclub and felt inferior, after noticing how big it was. However, Ellington eventually got over his insecurities, by having sex with Eva Gabor. Once this became public knowledge, people were amazed at how a black man could have sex with a beautiful white woman, which helped him gain his self-respect back. Duke tells Nick that if he wants to feel better about himself, then he should go out with the prettiest girl in his school and Nick is convinced to do just that.
The next day at school, Missy reminds Andrew, Jessi, and Jay about the dance and how the theme is Ancient Mesopotamia. Jay does a magic trick but Missy ruins it by revealing his secret. Jessi tells Jay that she never cared to begin with and Jay gets pissed off and starts throwing a tantrum. Nick happily walks in and spots the hot 8th grader, Olivia and immediately goes right ahead to ask her out. Olivia says that she'll gladly go with him and they officially become a couple. Nick's friends watch in astonishment from afar and Andrew gets mad about this. When Nick comes back, Andrew tells him that he thought they were going to the dance as a group of friends and that he's kind of mad that he bailed on him like that. Nick doesn't see anything wrong with this, saying that their plans to go as a group weren't exactly set in stone. During this little dispute, Maury manipulates Andrew's emotions, trying to make him get more and more angry at him. Andrew does just this and starts cursing in anger at Nick. Jessi tries to get Andrew to dial it back, while Jay pushes them to fight. Andrew finally tells Nick, "FUCK YOU!", which gets the attention of the other kids in the hallway, including Matthew, who records them on his phone, hoping to capture the impending fight. Before things can get too out of hand, Andrew holds back his anger and delivers a calm "Just, ... fuck you man." to Nick, before grumpily trudging away, leaving Nick feeling sad for both himself and Andrew. Jay coughs up a card and asks Jessi if it was her card. Jessi says that it wasn't and Jay gets pissed off and starts screaming like a pissed off idiot again.
On the night of the dance, Andrew goes to the dance and meets up with Missy there. Missy asks him where Nick is and Andrew just tells her that they decided to be alone. Coach Steve tries to become friends with the other teacher but they all just blow him off. Matthew comes up and Coach Steve tells them about how cold the other teachers are and Matthew calls them a gaggle of rancid cunts. Coach Steve is a bit blown away by the language, saying that his insult was a bit extreme, but he believes that they're basically on the same page. Jay tries to wow Devin and Lola with his fire magic but they freak out because they're wearing hairspray. So they scream in anger and call him a psycho. Jay tells Andrew that Nick is at the dance, but Andrew just says that he and Nick aren't friends anymore. Meanwhile, Nick goes up to Jessi and tells her about his date with Olivia. Jessi tells him that Olivia isn't the sharpest tool in the shed and asks why he keeps looking at Andrew. Nick denies looking at Andrew and also denies Olivia's stupidity. Olivia arrives and Nick goes up to talk to her. Olivia tells him that she's breaking up with him at that now, she's going out with Dylan, who's a ninth-grader, making him more desirable than anyone else. Nick cries over this and Andrew feels bad for him. Missy comes up to Andrew and asks him to dance. Andrew begins to turn Missy down to go check on Nick, but Maury comes up and convinces him to dance with the girl he loves. Andrew goes along with it and the two have an awkward slow dance together. Meanwhile, Jessi goes up to Nick and tells him "I told you so." over the thing with Olivia. Coach Steve bothers the DJ and gets him to play "Lady in Red", which he obnoxiously sings out loud.
Nick and Jessi have a talk out in the halls and then they start making out. Back at the dance, Maury gets Andrew a little too excited during his dance with Missy and gets him to jizz his pants. Andrew runs to the bathroom and finds that his pants are full of cum. He tries to wash them out in the toilet but he falls into the toilet and starts talking to his sperm cells. As Andrew climbs out of the toilet, Nick comes in and sees what he's doing. Andrew tells Nick that he's been mean to him all week and he doesn't know why. Nick says that it's because he saw his bug dick and it made him feel bad about his own dick. Andrew tells him the whole story and Nick gives Andrew his pants and goes to the dance in his underwear, making a sacrifice for his friend.
That night, Nick and Andrew have a sleepover once again and Nick is awoken by Maury coming in. Nick asks who he is and Maury tells him not to mind him, as all he's doing is giving Andrew a nocturnal emission. Maury uses his magic to make Andrew jizz the bed. Nick asks Maury if he's the puberty fairy, which pisses him off. Maury says that he's the hormone monster and although he usually fucks with dudes, he's not a "fairy".
- Matthew MacDell
- Missy Foreman-Greenwald
- Elliot Birch
- Diane Birch
- Barbara Glouberman
- Marty Glouberman
- Coach Steve
- Duke Ellington
- Devin (Cameo)
- Lola Skumpy (Cameo)
- Leah Birch (Non-Speaking)
- Judd Birch (Non-Speaking)
- Lump Humpman (Non-Speaking Cameo)
- Susan (Hallucination)
- Roland (Pictured)
- Connie (Name Written)
- Cyrus Foreman-Greenwald (Mentioned)
- Andrew Glouberman is the first character to speak in the series, not counting the narration voice of the unimportant woman in the female sex-ed video.
- It's revealed that Duke Ellington died in The Birch House and that his ghost still haunts the attic.
- Nick has a cat clock in his room, that was given to him by his grandmother.
- When hallucinating people as penises, Nick visualized Jay as an uncircumcised penis, implying that Jay might be uncircumcised.
- Apparently, despite Bridgeton being a middle school, they still have 9th-grade classes. Dylan is mentioned as being a 9th-grade student and he goes out with Olivia, an 8th-grade student.
- Missy practices slow dancing with her dad.
- Maury rolled up his sleeves, while pushing Andrew to curb stomp Nick, revealing to have a tattoo on his arm, that says "Connie", with the "i" being dotted with a heart. This was foreshadowing Connie the Hormone Monstress before she would appear in "Everybody Bleeds".
- Nick has a picture of Roland on his wall. We would later learn more about the girl in the picture and her significance in Nick's life in "Pillow Talk", when Roland makes her first appearance.
- Jay claims that he's going to fill his pillow with Jay jizz tonight. In "Pillow Talk", we discover more about Jay and his habit of fucking his pillows.
- Coach Steve admits to living in a storage unit. In "Steve the Virgin", Coach Steve's home in Deep Queens Self Storage would make its first appearance and be explored.
- Devin and DeVon are seen slow dancing together at the school dance. In "Everybody Bleeds", the two are revealed to be an official couple.
- Maury tells Andrew that when he cums in his pants, his underwear is going to look like art by abstract artist, Jackson Pollock, who's art was just him splattering paint all over an easel.
- According to the show's lore, Duke Ellington died in what is now the home of the Birch family. In reality, Duke Ellington died at the age of 75, on May 24th, 1974 in New York City. He did not live in a suburban home, nor did he even die in his living residence. After moving to New York, Duke lived in Apartment 4A at 935, St. Nicholas Avenue, in an apartment, that is now known as The Duke Ellington House and his place of death was in The Columbia Presbyterian Medical Center. 
- Maury watches the sex scene from Dallas Buyers Club with Andrew and thinks about AIDs.
- Duke Ellington says that back in 1938, he caught a glimpse of Charlie Parker's penis in the bathroom at the New York night club, The Cotton Club, where they used to perform and felt emasculated, due to Parker's superior dick size. Ellington also notes that Charlie Parker's pubic hair looked like feathers, which is how he got the nickname "The Bird".
- Duke Ellington had sex with Eva Gabor to help him forget about how much bigger Charlie Parker's dick was, when compared to his own.
- The theme of the school dance is Ancient Mesopotamia.
- Matthew compares Nick to Brian Grazer.
- Matthew calls Nick and Andrew "Laurel and Farty", which is a pun on the comedic duo, Laurel and Hardy.
- Duke Ellington remembers how he and his saxophonist, Cornell Dupree (who he for some reason addresses as "Studs") got into a fight. Duke said that Cornell died from a heroin overdose. In reality, Cornell Dupree died of emphysema (shortness of breath).
- For the dance, Missy dresses up as the Mesopotamian goddess, Nanshe and accurately describes her as the goddess of social justice and fishing. Both of which were things that Nanshe was known for being deemed the "goddess" of.
- Andrew jokes that he'll be paying admission to the dance with Ancient Mesopotamian silver and Missy laughs and corrects him, saying that silver mines were not actually operational until the Mid-Bronze age.
- Maury insults Nick, by referring to him as the video game character, Pikachu.
- Coach Steve sings the Chris de Burgh song, The Lady in Red.
- Andrew diving into the toilet to retrieve his jeans, as well as an interior view of him swimming in there and emerging from it is a reference to the "worst toilet in Scotland" scene in Trainspotting.
- The song "I Don't Wanna Grow Up" by The Ramones plays during the ending credits.