Turns out Kieran Culkin is more of “A Real Pain” than his recent Golden Globe-nominated performance suggests. In a recent interview with The Guardian, the “Succession” actor revealed that almost 25 years ago, while performing in a production of James Lapine’s “The Moment When,” it was he who switched Mark Ruffalo’s prop joint for one filled with real marijuana, forcing Ruffalo to perform high during opening night of the show. Ruffalo had previously recounted this experience in 2012 on The Graham Norton Show while promoting the first “Avengers” film.

“There was a play that I did that I smoked a joint in the first scene,” said Ruffalo, “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.”

Consummate professional that he is, Ruffalo did not reveal...