You've probably heard some motherly person say, "It isn't polite to laugh at others' expense."
That probably hasn't always stopped you, either. Let's face it: Whether you were a bully in school or the kid getting picked on, you've found yourself breaking this rule at some point.
We may think of cruel laughter as insensitive and out of touch today, but it's been around for a long time [source: Morreall]. In the late Middle Ages, for instance, there's record of residents buying a condemned criminal from a different town just so they could enjoy quartering him themselves [source: Morreall].
Add to that derisive laughter's place in ancient texts. It appears several times in Homer's "Iliad" and even in the Bible [source: Morreall].