A few from Rodney Dangerfield:
"I was such an ugly kid… when I played in the sandbox, the cat kept covering me up."
"I was so ugly my mother used to feed me with a sling shot."
"In the school I went to, they asked a kid to prove the law of gravity and he threw the teacher out of the window."
"I drink too much. The last time I gave a urine sample it had an olive in it."