Jimmy Fallon cracks up as Jack Black's pants drop during entrance

Jack Black made a hilarious entrance on The Tonight Show Starring Jimmy Fallon, accidentally revealing his red and black boxers.

The 55-year-old actor, who is gearing up for his upcoming project, A Minecraft Movie, made a surprise appearance at the late-night show on Monday, March 31.

During the show, the Dear Santa star was jamming on an electric guitar when things took a funny turn.

As the American star moved towards Fallon, his pants slipped down, exposing his red and black boxers, causing the audience to burst into laughter.

Reflecting on the hilarious moment, the 50-year-old said, “You bring the heat! You bring the energy.”

The Goosebumps actor jokingly responded, “I didn't bring a belt. That's what I didn't bring.”

Black, who is starring alongside Jason Momoa in the adventure/comedy film, is also set to host Saturday Night Live this weekend.

During his conversation with Fallon about hosting SNL, he recalled his past appearances, saying, “Dude, the first time I hosted - because I hosted thrice - I don’t want to hoot my own horn, thrice! I remember it was 25 years ago and the musical guest was The Strokes.” 

A Minecraft Movie, directed by Jared Hess, is set to be released on April 4.