Sam Rockwell Drops F-Bomb in 'SNL' Debut

Sam Rockwell made quite the first impression during his time hosting Saturday Night Live over the weekend.

In a bit titled "Science Room," the actor played a scientist holding a demonstration for two kids. While doing an experiment with oil and water, his character asked the kids (played by Mikey Day and Cecily Strong), "You put the oil into the water, and the oil is...?" One of the kids, named Josh, answered, "False?" At which point Rockwell starts losing his temper, and replied, "This isn't a true-or-false, Josh — you can't be this fucking stupid!" 

Rockwell presumably noticed his mistake, putting his hand briefly over his mouth. He then went on to yell, "Come on! Just look at it! The oil went down into the water and then it went back to the...," at which point, the kids interrupt with, "Back to the Future?"

It was the Three Billboards Outside of Ebbing, Missouri star's first time hosting the show. The musical guest was Halsey.

See a clip of the moment posted by a viewer below.