Wonder what Fergie thinks about this.

In a new behind-the-scenes clip for Nickelodeon's Fanboy & Chum Chum, Josh Duhamel and Jamie Kennedy show off their goofy sides, wearing their underpants outside of their pants!

"Why is it so awesome working with Fanboy and Chum Chum?" Duhamel, 38, asks.

"Those guys are our idols," Kennedy, 41, quips of the animated characters. "We wanna be just like them."

Check out Duhamel and Kennedy -- wearing their underwear on the outside of their pants -- in the clip above!