Here's some I like:
"If you were a door, I'd bang you all night."
"My name's Doug, that's God spelt backwards with a little bit of 'u' in it."
"If you were my homework, I'd do you all night on my kitchen table."
"The only thing your eyes haven't told me is your name."
And of course "How much does a polar bear weigh? Enough to break the ice."
Yes, I've heard all of these