LOS ANGELES — It’s been a few years since “Mystery Science Theater 3000” went off the air, but on April Fool’s Day, the “MST3K” trio of Mike Nelson, Kevin Murphy and Bill Corbett will be back on TV. But instead of mocking cheesy old genre films, they’ll be tackling National Geographic Channel’s own programming.

“Total Riff Off” is NatGeo’s April 1 special event featuring three hours of clips from their shows, including “Honey Badgers,” “Unlikely Animal Friends,” “Man v. Monster,” “Swamp Men” and “Alpha Dogs” among others. Nelson, Murphy and Corbett will provide the wisecracks.

The event has been broken up into three hour-long episodes.

“Mystery Science Theater 3000” ended in 1999, but in 2006, Nelson began RiffTrax, an online source of commentaries on a wide variety of films, not necessarily low budget sci-fi flicks. Murphy and Corbett soon joined him and they have recorded commentaries for such big budget films as “The Avengers” and “The Hunger Games.” Unlike the old “MST3K” episodes, these tracks are sold independent of films themselves.

While the cast of “MST3K’s” later years has been doing RiffTrax, the show’s creator, Joel Hodgson, has been doing something similar called “Cinematic Titanic” with other former contributors to “MST3K” including Trace Beaulieu and Frank Coniff.