Shemar Moore on His 'Criminal Minds' Costars

While the cast of Criminal Minds has to keep a serious demeanor on camera while going after bad guys, behind the scenes the cast can goof off with the best of them as Shemar Moore revealed during his visit to the ET stage.

While there was some discrepancy in regards to who was the biggest prankster on the set, no one denied the frequent occurrence of some pretty outlandish practical jokes.

"Somehow there was a real bear on the set in the woods one day," said Thomas Gibson, describing a prank put together by Matthew Gray Gubler to scare Shemar. "I think it worked, but I think that Shemar pretended that it didn't."

Joe Mantegna is another guy who always keeps his cool, and he explained why nothing on the show freaks him out, saying, "I'm trying to portray a real-life job that is sometimes very demanding as honestly as possible."

You can catch new episodes of Criminal Minds Wednesdays on CBS. And be sure to watch ET on Wednesday, November 9 as Shemar co-hosts alongside Nancy O'Dell while Mark Steines is on assignment.