Kangas believes it's the clown's face that bedevils. A grinning, mocking skull is how one clown hater on the Internet describes classic whiteface. Some people fear anything with a covered face. The Easter Bunny. Santa Claus. Bozo.

"I think part of the fear is because people in masks make us uncomfortable, and clowns have masks that are painted on their faces," Kangas says. "It may even be creepier because the masks can move, since it's only paint. Another thing is the smile that's painted on is artificial, and I think kids pick up on that deceit when they see a clown for the first time.

"They can't see the clown's real face. A lot of those kids will react to the deception with distrust, maybe even fear. ... Those kids take their fear into adulthood."