"Turpentine," the kid replies. "The most powerful thing in the universe."
The priest studies the bottle reflectively for a moment, then says, "Son, the most powerful thing in the universe is holy water. If you rub it on a pregnant woman's stomach, she'll pass a baby boy."
The kid says, "Shit, that ain't nothin'. You rub this on a cat's arse, it'll pass a motorcycle!"