“Science Room” was an unremarkable sketch—especially for the first one after the monologue—but it still made SNL history on Saturday when host Sam Rockwell accidentally dropped an unbleeped f-bomb in front of two cast members playing small children.

As his vintage science TV host character got more and more exasperated with his students, Rockwell went off-script and yelled at them, “You can’t be this fucking stupid!”

The actor, who won a Golden Globe this past week for his role in Three Billboards Outside Ebbing, Missouri, immediately caught himself and realized he’d messed up. Cecily Strong comically put her fingers in her ears and Mikey Day’s jaw dropped in mock horror.

An uncensored f-bomb on live TV in the middle of the night shouldn’t be that big of a deal, but it has somehow only happened a handful of times in Saturday Night Live’s 43 seasons. The last time was in 2009 when cast member Jenny Slate, in her first-ever episode and sketch, accidentally said “fuckin’” instead of “friggin’.” She stuck around for the rest of the season, but was not asked to come back the following year, a decision that some speculated had to do with the fateful f-bomb.

The most famous instance of a cast member saying “fuck” on SNL happened in 1981 when Charles Rocket said the word on-air and was quickly fired mid-season. Norm Macdonald said the word on “Weekend Update” shortly before he was fired for a totally different reason.

Hosts and musical guests from Prince and Steven Tyler to Samuel L. Jackson and Kristen Stewart have all accidentally said the f-word on SNL. This week, “Weekend Update’s” Colin Jost and Michael Che both said the word “shithole,” although they were quoting the president of the United States.