J.P. Manoux, sans pants.
The clip is from an episode of Comedy Central's Reno 911!, a parody of COPS that features mostly improvised dialogue.
I'm pretty sure he was naked before this, on CBS's Nash Bridges, too, back in 2001... he did a piece on All Things Considered about it.
You can catch JP in the upcoming direct to DVD sequel to the new Steve Carell Get Smart movie, an upcoming episode of Monk, some ER, and The Emperor's New School.
Oh, and check him out backing up Vince Gill.