Hollywood prankster Clooney, who was best man at the former SPIN CITY star's 1999 wedding to DANA STANLEY, worked on the elaborate plan for 12 months, before putting his pal through the two-year embarrassment.
He says, "I remember finding a painting that someone had thrown away. It was out by the garbage and I drove by it a few times. They were waiting for the trash collector to pick it up. 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. So they would show up and go, 'That's an amazing painting!' and he'd be (confused)."