You Can't Do That on Television, Season 3 (1982)

Elizabeth was sent to detention for putting on makeup in class, and has just been busted by the principal for putting on more makeup in detention.

Principal:
Elizabeth, you know it's against the rules to wear makeup during school hours!

Elizabeth:
But sir, it's after school hours now, isn't it?

Principal:
It's still against the rules to wear makeup in school.

Elizabeth:
Oh, dear. Well, I don't want to break any more rules. I guess I'd better leave right away.

Principal:
I guess you'd better. And let this be a lesson to you, never to wear makeup in school again.

Elizabeth:
All right, I won't. [She leaves]

Principal:
[Suddenly realizing he's been tricked] ...Wait a minute!... Just once, why can't I win just once?!