Pasted from an article:
One of Clooney's more elaborate pranks involved a canvas painting he gifted to best pal and actor Richard Kind. "I remember finding a painting that someone had thrown away," explained Clooney. "It was out by the garbage and I drove by it a few times. It was this gigantic, awful painting. I finally stopped and picked it up and took it home and signed my name to it and framed it. And for about a year, my buddy Richard would go, 'Hey, you want to play golf?' And I'd go, 'I can't. I've got art class.' And then on his 40th birthday I said, 'My art teacher's really proud of me but this (painting) is the first one we're both really proud of. You've been so supportive, I want you to have it.' It hung over his couch for another two years and everyone knew except for him."
You're probably thinking..that's not very sociopathic. But then you have:
This is some vintage Clooney. In 1993, fresh off his divorce from Talia Balsam, George temporarily moved in with old friend Richard Kind. It turns out the Spin City star kept his cat's litter box in the guest bathroom, which George (his guest) was using. Each day, George would empty the litter box but say nothing to Richard. Naturally, Richard began to worry that his feline was woefully constipated — and eventually took the cat to the vet. Clooney then left his own special "present" in the box instead. Oh, George!