(NewsNation) — Kevin O’Leary, the steely venture capitalist known paradoxically as “Mr. Wonderful,” is dishing on his first big screen acting role, which required him to administer a spanking to co-star Timothée Chalamet.

The 71-year-old Canadian makes his debut in the critically acclaimed period piece “Marty Supreme,” about an unlikable table tennis prodigy (Chalamet) who pushes for a sponsorship from a rich entrepreneur (O’Leary). O’Leary’s character agrees to the deal but insists on walloping the athlete on his (bare) bottom with a paddle.

“When it came time to whack him, there was a stunt ass. There was a double,” O’Leary told “Variety” recently. “[Chalamet] said he’ll do it himself. He didn’t want some other ass immortalized.”

The fake prop set aside for the stunt broke on the first take, so O’Leary used a real paddle for a scene that he said required dozens of takes at the insistence of director Josh Safdie.

“Josh was saying, ‘You’ve got to wind up harder,’” O’Leary said. “I was really whacking him.”

“Marty Supreme” has been a hit for film studio A24, grossing $43.4 million to date domestically, and is considered a contender for major movie awards.

O’Leary said Safdie, who co-directed the cringey Adam Sandler thriller “Uncut Gems,” told him he was looking to cast a “real a—hole” for the part and added, “You’re it.” O’Leary said he got a similar pitch 20 years ago when a TV producer was assembling an intimidating panel to star on “Shark Tank.”

“I’m starting to think this a–hole thing’s working for me,” O’Leary said.