Father of One of My Kids:

A Guy goes to a supermarket and notices a beautiful blonde waving at him and says hello.

He's rather taken aback, because he can't place where he knows her from, so he says, "Do you know me?"

To which she replies, "I think you're the father of one of my kids."

Now he thinks back to the only time he has ever been unfaithful to his wife and says, "My god, are you the stripper from my bachelor party where I laid on the pool table with all my buddies watching, while your partner whipped my butt with wet celery and then stuck a carrot up my butt."

She said, "No, I'm your son's math teacher".