Kieran Culkin Admits to Getting Mark Ruffalo High on Stage in Hilarious Theater Prank

Kieran Culkin, 42, recently opened up about a mischievous moment from his youth, revealing how he accidentally got Avengers star Mark Ruffalo high during a theater performance. In an interview with The Guardian, the Succession actor shared the story of swapping a prop joint for real marijuana on the opening night of The Moment When, a 2000 play starring Ruffalo and Broadway legend Phyllis Newman.

"I was 17 and stupid," Culkin admitted. "As soon as I smelled the weed, I realized it was a terrible idea."

Despite his initial regret, the prank turned out to be surprisingly well-received by his co-stars. Ruffalo, then 37, was amused, saying, "I haven’t smoked pot in 10 years; the second half’s going to be so much fun." Newman, meanwhile, laughed it off, reminiscing about her last joint in the 1960s.

However, not everyone was thrilled. The stage manager quickly intervened, confiscating the joint and sternly warning Culkin, “Ruin your life on your own time.”

Culkin’s pranks didn’t stop there. Years later, while performing in Kenneth Lonergan’s This Is Our Youth with Colin Hanks, he joked about pulling a similar stunt. Initially, Hanks warned him, "If you ever do that, I’ll punch you in the face." But as the play progressed, Hanks seemed to warm up to the idea.

One night, Culkin handed Hanks real marijuana for a scene. The unexpected switch left Hanks so flustered that he struggled to roll the joint, ultimately resorting to a fake prop as the audience remained oblivious.

Reflecting on his antics, Culkin admitted, “I’m 42 now. I know better. I’m not going to try to get anyone high on stage.”

Interestingly, Mark Ruffalo shared his side of the story in a 2020 appearance on The Graham Norton Show. Without naming Culkin, Ruffalo recalled the night he unknowingly smoked a real joint on stage. "I was taking dramatic puffs, thinking, ‘Wow, I’m really in it tonight.’ It was the best performance of my career—but don’t try this at home," he joked.

Culkin’s youthful pranks may be behind him, but the stories continue to light up conversations in Hollywood and beyond.