Buddy Hackett told this joke on an HBO special back in the ‘80s. It’s not my favorite joke of all time, but it’s definitely my favorite punch line.
An 80-year-old man and a 20-year-old woman fall in love. They want to marry, but the old man fears that he won’t be able to satisfy his young bride. Then they hear about an experimental surgery that’s being done for couples just like them. The surgeon replaces the man’s penis with the trunk of a baby elephant.
After long and careful consideration, the man has the surgery, and it works out beyond their wildest expectations. After a blissful weekend in bed, they decide to move forward with the wedding.
Naturally, the girl’s parents want to get to know their future son-in-law, so they invite him to dinner. Although they are concerned about the difference in ages, they can tell that their daughter is really in love.
In fact, she can’t keep her hands off her fiancé. Under the cover of the tablecloth, the girl unzips the old man’s pants and begins fondling him. All the while, above board, the couple chats with the girl's parents about their wedding plans.
It is as the mother sets out a tray of potatoes that an elephant’s trunk shoots out, curls around a baked potato and drags it beneath the table.
The girl’s mother’s mouth falls open. Her eyes trace the path from the old man to the serving platter and back again. After a stunned moment, shaken, she clears her throat and says, “That was amazing. Could you do that again?”
And the old man says:
“I would, but I don’t have room in my ass for another potato.”
(Note: Despite the reputation I've acquired at Belle's house, no baby elephants were harmed in the telling of this joke.)