The Andy Griffith Show S04 E08 Opie's Ill-Gotten Gain

"Nip it in the bud!"

Opie finally gets a good grade in math, and Andy is so proud he tells everyone in town. But when Opie's teacher tells him she made a mistake and his grade is actually an F, he goes home to tell Andy the bad news, only to find Andy has bought him a shiny new bicycle.