Steve shocks his family by announcing he has entered puberty.
Season: 4 Episode: 1
Total Episode Count: 59
Prod. no.: 3AJN20
First Aired: September 28, 2008
Guest Starring: Elizabeth Banks
Featuring: Steve Smith, Stan Smith, Francine Smith, Roger
Also Appearing: Hayley Smith, Klaus, Barry, Snot, Toshi, Lisa Silver, Janet Lewis, Amy, Vince Chung, Aiden
Musical Numbers: Good Morning USA Ver. 2, I Don't Want to Wait
Director: Caleb Meurer
Assistant Director: Mike Mayfield
Writers: Rick Wiener, Kenny Schwartz
Storyboarders: Erik Kuska, Steve Wong
Roger's Disguise: Normal Self
Plot: As Klaus shows off his new hamster ball filled with water to enable him to move around the house, Roger is excited to see that the family is setting up for his 1,600th birthday party, a milestone for his people. But Steve runs down the stairs and reveals he is going through puberty when he has grown his first pubic hair. Stan and Francine are shocked because Hayley's puberty didn't go well for them, as she had wild mood swings for every single development, having to wear tampons, annoyance that her breasts were too small, and face acne. Steve begins to show off his puberty to his friends and across the school. Steve later asks Lisa Silver out to meet her at Macy's. Francine, not wishing to go through the same trauma again, then goes to the CIA. She bribes the lab scientists and injects Steve with a needle to stop him from aging further for at least a few more years. However, the serum makes him a toddler all over again.
This angers Steve and he asks who did it to him. Francine confesses she injected him with it, but Stan distracts Steve with cartoons. Steve goes to the mall with Francine where he was supposed to meet Lisa to buy her a prom dress. Lisa is thinking that Steve's appearance is a joke and that he is Steve's nephew. That night, Stan injects him with a needle, also from the CIA, in order to settle Francine's mistake and to make Steve an adult, to skip Steve's puberty instead of holding it off. However, much like the first attempt, the new serum is too powerful and turns Steve into an old man. Steve is just as furious as before, saying he has pubic hair, but it is white. Stan says he will head back to the lab and get an antidote, distracting Steve yet again with the television, this time with The Weather Channel.
Klaus tells Steve that Lisa called to meet him again. Steve comes up with a story that he traveled back in time from 80 years into the future. He manages to meet with Lisa and tell her the story, but all it does is confuse her and cause her to leave the date as he falls asleep before Francine finds him. Stan comes home with the antidote to turn Steve back into a fourteen year old. But as they complain about the bad effects of puberty, Steve runs off. Roger drops Steve off at a bus stop and Steve leaves on a bus with an old woman and reveals he doesn't want to be put in another situation where it involves his age.
Francine is looking for Steve until she and Stan find out Roger dropped off Steve so he can celebrate his birthday party. Steve, who is now in a retirement home, gets a call from Stan to come back to the house. But Steve wants to stay because he enjoys his new life and threatens to kill himself, making Francine and Stan feel guilty for changing the most important years of his life. Francine and Stan find Steve and they give him the shot just in time for the dance. He finally dances with Lisa, but a drunk enraged Roger pulls down his pants to show he only has one pubic hair, ruining his moment. The bullies then give him a swirlie and Stan and Francine reveal that puberty isn't perfect for anyone. The pubic hair from Steve floats across town until Roger comes home from the dance. Roger is upset that Steve stole his thunder and nobody remembered his birthday. However, Klaus is shown with a birthday cake reading, "1600" and a single candle. Roger says that his wish came true, but the pubic hair lands in the cake. After all that albeit unintentionally, Steve has still found a way to spoil Roger's 1,600th birthday. The episode ends with Roger saying, "I hate Steve so much".