The Simpsons (1989): Season 27, Episode 11

27 - 11: Teenage Mutant Milk-caused Hurdles

A new teacher at Springfield Elementary, and a captivated Bart tries everything to win her over. Meanwhile, Homer decides to buy a new brand of "milk," which causes early puberty, both for Bart (augmenting his wooing powers) and Lisa (whose small bout with acne opens her up to the world of makeup and popularity).