A guy walks into a bar wearing a huge hat. He sits down and orders a drink.

"That's a really huge hat!" the bartender says.

"Yeah," the guy says. "I had a really big head!"

The bartender stares at the man's normal-sized head in confusion.

"No, you don't understand," the man says. "I mean I HAD a really big head. Past tense."

He removes the hat to reveal a shrunken, raisin-like head perched atop his normal body.

"Turns out hats can be load-bearing structures," the man says casually as his tiny head wobbles. "Who knew?"

The bartender faints. As he hits the floor, his own head inexplicably swells to massive proportions.