Encouraging Fun Loving People to Read and Enjoy Funny I Am A Dentist Joke from The Quality Collection of Doctor Jokes.
Two psychiatrists with offices in the same building rode the elevator together every morning. Each day, the elevator operator would watch in amazement as one of the psychiatrists spit in the other's face, while the victim did nothing in return.
Finally the operator stopped the second man after the other had exited and said, "Excuse me, sir, but for three years I've been watching that other man spits in your face every day. I just have to ask why you don't ever do anything about it."
"Well," said the shrink, "it's HIS problem."