A man is in the Super Market produce aisle when he notices a rather dishy
 blonde across from him raise her hand and smile hello. He is rather taken
aback that such a looker would be waving to him, and although familiar he
can't place where he might know her from, so he says "Sorry, do you know
me?"

She replies "I may be mistaken, but I thought you might be the father of one
of my children!"

His mind shoots back to the one and only time he has been unfaithful.

"Christ!" he says "are you that stripper on my stag night that I screwed on the
pool table in front of all my friends whilst your friend whipped me with some
wet celery and stuck a cucumber up my ass?"

"No" she replies, "I'm your son's English Teacher"