I had a very Tommy Cooper-esque experience at the doctor's this morning. The conversation went like this (this is no word of a lie):
Me: It hurts every time I touch my knee.
Dr: So why do you keep touching it then?
Me: To see if it hurts!
If you're not familiar with the British magician/comedian Tommy Cooper, watch the following video. At 3 minutes and 30 seconds he tells the doctor joke I was alluding to in my first sentence.