Culkin and Ruffalo shared the stage in Playwright Horizons' 2000 production of James Lapine's "The Moment When."

Mark Ruffalo revealed how he handled being pranked by Kieran Culkin - who swapped a prop joint for a real one - on the opening night of a play in 2000.

Kieran Culkin has confessed. The star of “A Real Pain” and “Succession” admitted that he once swapped a prop joint for one spiked with real marijuana when he was cast in a stage production alongside Mark Ruffalo in 2000.

Succession star Kieran Culkin recently opened up about getting actor Mark Ruffalo ‘high’ long ago as part of a prank, when they were filming a stage production together. This has sparked intrigue amongst fans who wish to learn the details about the same.

Kieran Culkin opened up about getting Mark Ruffalo, 57, high while they were in a play together by swapping a prop joint for real-life marijuana.

Kieran Culkin has admitted he's the "naughty young actor" who once got Mark Ruffalo high during a play by replacing a prop joint with a real one.

In a new interview with The Guardian, Kieran Culkin makes a point of saying that he doesn’t do drugs and never has—with one pretty major exception. In 2000, Culkin performed in The Moment When, an off-Broadway play written by James Lapine.

With a stash of prop joints backstage, Culkin couldn’t resist the temptation to swap one out. “Uh-oh. I believe it’s happened,” he thought to himself weeks later as he caught a familiar scent and “just watched” Ruffalo take a hit before passing it to their co-star.

After Mark Ruffalo said a "naughty young actor" once got him high on stage when switching a prop joint for the real thing, Kieran Culkin came forward.

Kieran Culkin has admitted that he once swapped a prop joint for a real one while acting in a play alongside Mark Ruffalo earlier in his career.