Kieran Culkin reveals wild prank that got Mark Ruffalo high

Kieran Culkin opened up about a prank he pulled on Mark Ruffalo.

In an interview with Guardian, the 42-year-old actor admitted he once got the 57-year-old star high during a play by swapping a fake joint for real marijuana. 

The Succession alum then reflected on being "17 and stupid," when he switched the prop with a real one during the opening night of the 2000 play The Moment When, which starred the Now You See Me star and Tony Winner Phyllis Newman. 

As soon as the scent of weed reached Kieran, regret washed over him as he went on to confess that he felt extremely guilty at first, and was terrified for the consequences, apologising profusely, but was surprised to find out that everyone enjoyed it. 

"Mark says, 'I haven’t smoked pot in 10 years; the second half is going to be so much fun,'" he told the outlet.

"There was this other actor who had never smoked pot in her life. She goes, 'Is this what being high is? This is lovely,'" he added.

"And then Phyllis comes in and goes, 'I haven’t smoked pot since the 1960s. Thank you, darling,'" the Emmy Award winning actor continued.

However, there were people who were not pleased with the prank the Golden Globe Award winner pulled.

He playfully explained that the stage manager stormed in and demanded the joint, saying, "'I don’t care whose it is, or what happened, but Kieran, give me the joint. I sheepishly handed her the roach and she said, 'Ruin your life on your own time.'"