Because they're lazy, and they hate U.
An American
We don't like anything white on our land.
Because it was soda pressing.
Cis-tem of a Down
Smiles - because there is a mile between the first and last letters
A Preppysition
Kay (K).
The Post Office
Motorist: I was making a U-turn and changed my mind.
Husband: Because Nobody Carries A Tiffin To A Restaurant. "If U Didn't Get It Go Watch Pogo":p