From one of the Carry On films... 2 doctors playing 'spot diagnoses' see a gentleman come in walking in a stiff manner. One guesses a slipped disk, the other guesses a hernia. They go and ask the gentleman:

"You thought I have a hernia? Well you were wrong. And you thought I had a slipped disk... you were wrong."

"Well what is wrong with you?"

"I thought I was going to pass wind. I was wrong."

LTS