A man was walking down a pier and saw a fisherman catching loads of fish. He asked him what he used as bait and the fisherman said he was a doctor and used extracted organs from surgery.
The man returned to the pier the next day and saw another fisherman catching loads of fish. That fisherman was also a doctor.
On the 3rd day, the man saw a fisherman with huge catches of fish, more than the other two men had. He asked him, "Doctor, what are you using as bait?" and the fisherman answered, "I'm not a doctor, I'm a rabbi."