Lil' Johnny went to the drugstore for some condoms.  He walked up
 to the druggist and asked, "Sir, can you tell me where the ribbed
 condoms are?"

    The druggist asked, "Son, do you know what condoms are used for?"

    "Sure do," replied Johnny, "they keep you from getting veneral
 diseases."

    "O.K." said the druggist, "do you know what the ribs are for??"

    Lil' Johnny thought for a minute, then looked up at the druggist
 and replied, "Well, not exactly, but they sure do make the hair on my
 goat's back stand up."