Sam Rockwell dropped an f-bomb on Saturday Night Live and the cast just about held it together

Sam Rockwell is, in this writer's opinion, one of the most underrated actors in all of Hollywood.

His filmography includes the likes of Moon, The Way Way Back, Frost/Nixon, Seven Psychopaths and The Assassination of Jesse James to name but a few.

The Golden Globe winner can even accidentally swear on television and somehow hold it together (just).

The 49-year-old guest hosted the weekend's episode of Saturday Night Live to promote his latest role in the new movie Three Billboards Outside Ebbing, Missouri.

In a segment called Science Show Rockwell plays a science teacher, aptly named Mr Science, whose patience is tested by a pair of students who aren't the sharpest knifes in the drawer.

After conducting an experiment involving water and cooking oil, the students struggle to comprehend the simple meaning of the lesson.

As Mr Science gradually loses his cool, Rockwell went off script and accidentally dropped the f-bomb on live television, much to the shock of the audience and his co-stars, Cecily Strong and Mike Day.

The moment was captured by Dave Itzkoff on Twitter, the culture reporter for the New York Times.

Warning: This clip obviously contains strong language.

SNL did put out an censored version of the segment on YouTube and although you can't hear the expletive the reaction is still just as palpable.

Thank goodness he's not a teacher.

More: New study finds sweary people are more honest