A man was standing next in line at a checkout, when the attractive blonde woman in front of him turned around and gave him a big smile.

"Hello," she said, as she waited for her change.

"Er, I'm sorry. Do I know you?" The man said in some confusion.

"Oh, my mistake. I thought you were the father of one of my children," she said apologetically, and picking up her shopping, she left the store.

The man was astonished. He thought, "How amazing that a good looking woman like that should have forgotten who fathered her children."

Then he began to worry. He had an encounter in his youth that could have resulted in a child he didn't know about. She had been blonde, pretty, and about the same height.

On leaving the store, he saw the woman getting into her car. He ran over to her and said: "Look, you couldn't have been the girl I met that night at a party in Hampstead, in 1980 could you? We shagged on the billiards table in front of everyone, things got really wild and I got so drunk that I didn't get your number."

The woman looked utterly outraged and said: "No! I'm your son's English teacher."