A guy goes to the supermarket and notices a very attractive woman waving at him.
She says, "Hello."
He's rather taken aback, because he can't place her. So he asks, "Do you know me?"
To which she replies, "I think that you're the father of one of my kids."
His mind races back to the only time he has ever been unfaithful to his wife.
He asks, "Are you the stripper at the bachelor party I made love on the pool table, while all of my buddies were watching?"
She looks into his eyes and says calmly, "No, I'm your son's teacher."