And psychologists wonder why kids are so often afraid of clowns. It's not just Pennywise from Stephen King's It who's to blame—sickos like John Wayne Gacy have been giving the colorful, supposedly playful jesters a bad name for decades now.

Gacy definitely takes the cake for the most sadistic clown of all time. The Chicago resident earned paychecks by dressing up as "Pogo the Clown" and attending various fundraisers and children's parties and performing for the little ones. Of course, the adults who hired Gacy didn't realize that, when he wasn't acting as lovable Pogo, he was sexually assaulting and subsequently murdering teenage boys in the years between 1972 and 1978—33 victims, to be exact.

He buried 26 of the corpses in the crawl space of his home, and spread three others out elsewhere on his property. Whether Gacy wore his clown get-up while killing has never been confirmed, and his May 1994 execution buried the answer along with him. But imagining so makes the story that much more nightmarish.

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