A Jewish boy was walking with his girlfriend on the grounds of his father's house. His father was a successful doctor, and was carrying out a circumcision in the on-site surgery. As they were walking, they heard a scream and a foreskin flew out of the window and landed at the girl's feet. "What's this, "she asked.
"Taste it," he replied, "If you like it, I'll give you a whole one!"