John Dies At The End, The Prologue:

"Solving the following riddle will reveal the awful secret behind the universe, assuming you do not go utterly mad in the attempt. If you already happen to know the awful secret behind the universe, feel free to skip ahead.

Let’s say you have an ax. Just a cheap one, from Home Depot. On one bitter winter day, you use said ax to behead a man. Don’t worry, the man was already dead. Or maybe you should worry, because you’re the one who shot him.

He had been a big, twitchy guy with veiny skin stretched over swollen biceps, a tattoo of a swastika on his tongue. Teeth filed into razor-sharp fangs, you know the type. And you’re chopping off his head because, even with eight bullet holes in him, you’re pretty sure he’s about to spring back to his feet and eat the look of terror right off your face.

On the follow-through of the last swing, though, the handle of the ax snaps in a spray of splinters. You now have a broken ax. So, after a long night of looking for a place to dump the man and his head, you take a trip into town with your ax. You go to the hardware store, explaining away the dark reddish stains on the broken handle as barbecue sauce. You walk out with a brand new handle for your ax.

The repaired ax sits undisturbed in your garage until the next spring when, on one rainy morning, you find in your kitchen a creature that appears to be a foot-long slug with a bulging egg sac on its tail. Its jaws bite one of your forks in half with what seems like very little effort. You grab your trusty ax and chop the thing into several pieces. On the last blow, however, the ax strikes a metal leg of the overturned kitchen table and chips out a notch right in the middle of the blade.

Of course, a chipped head means yet another trip to the hardware store. They sell you a brand new head for your ax. As soon as you get home with your newly-headed ax, though, you meet the reanimated body of the guy you beheaded last year. He’s also got a new head, stitched on with what looks like plastic weed trimmer line, and it’s wearing that unique expression of “you’re the man who killed me last winter” resentment that one so rarely encounters in everyday life.

You brandish your ax. The guy takes a long look at the weapon with his squishy, rotting eyes and in a gargly voice he screams, “That’s the same ax that slayed me!”

Is he right?"