An 80 year old man is given a jar to provide a sperm sample for the doctor. He turns up 2 days later with an empty jar. The nurse asks "why no sperm sample". He says "sorry, I tried with my right hand then my left then my wife tried with both hands and then her mouth, at first with her teeth in and then without. Then we got Ethel from next door to try, but it was no good. We just can't get the fookin jar open!