The new medical students!

Two young medical students were standing on a street corner observing people as they passed and discussing any abnormalities with each other that they may have seen in passers-by. They would then attempt to make the correct diagnosis.

They spotted this old fellow leaving a bar sort of "duck waddling" down the street at a slow pace. The two students introduced themselves to the gentleman and told him that they didn't agree with each others diagnosis of the his problem.

One says, "my friend thinks you have a bad case of hemorrhoids, and I think you have a hernia." Which of us is correct?

The old man replies, "Well fellas, I thought it was a fart, but it looks like we were all wrong!"