"Ghostly Hump" joke

Two drunks staggering home one night and one decides to take a shortcut through the cemetery. Half way through an apparition appears. "What's that on your back?" the ghost asks.

"It's a hump" says the drunk The ghost puts his hand on the drunk's back and the hump disappears.

He races home and next night at the pub he tells his mate all about it. His mate is amazed and says he is going through the cemetery that night as he has a wooden leg and wants a proper leg. Again half way through the cemetery a ghost appears... "What's wrong with your leg?" he asks.

"It's a wooden leg," says the drunk.

"Have you got a Hump?" asks the ghost.

"No" replies the drunk. So the ghost puts his hand on the drunk's back and says, "Here, you can have this one."