WARNING: This joke has an absolutely vile rating of 10.
David, the fisherman, had driven by the lake many times and had seen some other anglers about, so he decided to give his luck a try.
On his first day of fishing he had no luck at all but noticed that another fisherman near him that was scooping in one after another. He had to know The Secret. "Excuse me sir, but would you mind telling me what sort of bait you are using?" he asked.
The other man looked around a bit embarrassed. "Well, I am a surgeon, and quite by accident I found that human tonsil works very well."
David thanked the man, thought about what sort of bait to try next time, and left.
The next day, David returned to the lake, tried a different bait and still had no luck. Just as the day before, there was yet a different man reeling in fish after fish. "Excuse me," asked David, "but could you suggest a bait that I could try?"
"Well, I can, but I am not sure it will do you any good. I am using a bit of human appendix."
"Hmm," thought David. It seemed that the fish in this lake would require a little more effort than normal. He left, willing to give the lake one more try.
On the third day, David still had no luck. As was usual, there was yet another man near him bringing in fish left and right.
David wanted to confirm what he already knew. "Excuse me sir, but are you a doctor?"
"No, I am a Rabbi." replied the man.