'Kingdom' Star Jonathan Tucker -- I've Seen Nick Jonas Naked ... And It Was Awesome

Jonathan Tucker has seen what many wish they could've ... Nick Jonas naked.

Tucker is set to appear on this week's episode of "Allegedly" with Matt Weiss and Theo Vonn ... and he gives the scoop on Jonas' goods.

You'll have to take a listen to just how articulate Jonathan gets when describing Nick in his bday suit ... it's pretty funny.