An old bloke goes to see his doctor, accompanied by his wife. 

The doctor explains that in order to diagnose his complaint he will need a few samples "I need a stool, urine and semen samples from you", said the doctor. 

The old geezer was a bit hard of hearing and says to his wife, "Eh? What? What did he say?". 

His wife says, "he wants you to leave your underpants here".