The Simpsons (1989): Season 3, Episode 16

3 - 16: Bart the Lover

Bart's answer to detention from Mrs. Krabappel is to answer her personal ad with letters from a Mr. Wonderful, but his last laugh is more of a guilty whimper. Meanwhile, Homer makes a bet with Flanders that if he tries to stop swearing, Flanders will shave off his mustache.