Charlie wanted a new birth control method and his doctor suggested a vasectomy. Charlie agreed and the doctor said he could perform the operation in his office. At a crucial moment during the procedure one of Charlie's testicles fell to the floor, and the nurse not noticing, stpped on it, crushing it.
However, the doctor noticed a jar of pickled onions on his nurse's desk. Taking an onion, and realizing it was the right size and weight, he placed it in Charlie's scrotum and completed the operation.
A few months later Charlie returned for a check up.
When the doctor asked how things were going, Charlie replied. "Pretty good, Doc. My wife hasn't gotten pregnant, but there have been some strange side effects. Every time we make love, my wife gets heartburn; when I pee, my eyes water; and every time I pass a hotdog stand, I get an erection."