VIDEO: Jon Gruden and Frank Caliendo Have Hilarious Interaction on Set of 'Hard Knocks'

Comedian and impressionist Frank Caliendo has become popular for his spot-on portrayals of famous sports figures. Perhaps his best impression is Oakland Raiders head coach Jon Gruden, whom Caliendo can impersonate flawlessly in hilarious fashion. With Gruden now featured as one of the stars of HBO's Hard Knocks, Caliendo has brought back the Gruden impression, and the coach got in on the fun:

Unbelievable. I'm genuinely not sure which Gruden had a more accurate portrayal.

Gruden is a great sport about Caliendo's impression, and this is one of the best videos of the NFL preseason so far. Derek Carr seems pretty skeptical about the whole interaction in the background, though.

Caliendo originally brought back the impression after the first episode of Hard Knocks, when Gruden referenced the "Bluebonnet Bowl," which hasn't been played since 1987:

Keep the videos coming, Frank. They will literally never get old.