This was from a Martin Amis novel, The Information.
A mouse and a gorilla went out for a walk. Suddenly the gorilla fell down a hole. The mouse said, "Don't worry, I'll get the Porsche and pull you out." So he goes home, gets the Porche, gets a rope, throws it down to the gorilla, who ties it around his waist. The mouse ties the other end around the Porsche's bumper, puts it in reverse and pulls him out. Later when they resume their walk, the mouse falls down a hole. The gorilla says, "Don't worry," unzipping his fly. Just climb up my willy. And the moral of the story is if you have a big **** you don't need a Porsche.