Kieran Culkin has revealed himself as the “naughty young actor” who was responsible for getting Mark Ruffalo and other co-stars high during a Broadway production of The Moment When.

Ruffalo previously discussed the incident on The Graham Norton Show in 2012, but didn’t mention Culkin by name. “There was a play that I did that I had to smoke a joint in the first scene,” Ruffalo told Norton. “And of course, there was a very naughty young actor I was in the play with, who on the opening night with all the critics, he slipped a real joint onto the prop table.”

Now Culkin has admitted that he was the prankster who dropped an actual joint into the bag of prop joints. “I was 17 and stupid,” the actor told The Guardian in a recent interview, confirming that it took a few weeks for his prank to manifest itself. He said that during one particular show he smelled pot from the stage and realized, “Uh-oh. I believe it’s happened.” 

Not only did Ruffalo actually inhale on stage, so did Phyllis Newman. Culkin was asked to explain himself during the show’s intermission. “I’m like, ‘I thought this was a good prank. I’m stupid. Oh my God, I’m so sorry,’” he recalled. “But actually, they loved it. Mark says, ‘I haven’t smoked pot in 10 years; the second half’s going to be so much fun.’ There was this other actor who had never smoked pot in her life. She goes, ‘Is this what being high is? This is lovely.’ And then Phyllis Newman comes in and goes, ‘I haven’t smoked pot since the 1960s. Thank you, darling.’”

He continued, “Then the stage manager comes stomping in and goes, ‘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.’”

The actor added that he doesn’t still pull pranks, despite his inclination to do it. “I know, I know,” he told The Guardian. “But I was young. I’m 42 now. I know better. I’m not going to try to get anyone high on stage.”

When he first spoke about the prank, Ruffalo said he did actually get high on stage. “So, when you’re out at a party, you take two puffs and you say, ‘Okay, that’s enough. I’m so stoned,’” he said, adding that when he’s acting he tends to “overdo everything.”

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“Between the two of us, we smoked a giant blunt on stage,” Ruffalo said. “And I’m like, ‘Man, I am in it tonight. I feel it. I’m on fire. I’m feeling it… why’s that dude standing backstage laughing at me?’ And the kid who put the joint on the prop table is standing there, [laughing]. And I just went, ‘Oh shit.’”