Fred goes to the supermarket and, while there, notices a very pretty blonde waving at him and saying hello.

He is rather taken aback because he can't place where he should know her from.

So, he says, "Do you know me?" To which she replies, "I think you are the father of one of my kids." Now he thinks back to the only time he has been unfaithful and says, "Oh my God, are you the stripper from my friend's bachelor party that I screwed on the pool table with all my buddies watching, while your partner whipped my butt with wet celery stalks and then stuck a carrot up my ass?" "No" she said, "I'm your son's math teacher."