Rich Man, Poor Man (1976)

S7E13 Stew-Roids

After Stewie gets knocked around by Joe's baby daughter Susie, he decides to hit the gym with Peter. Just as he starts to notice some progress, Peter confesses that he's been secretly feeding him anabolic steroids. Meanwhile, Chris finds himself in a relationship with a girl who's well-liked at school, but her popularity quickly begins to dwindle.