David Giuntoli David Giuntoli

How can a Grimm attend a Wesen wedding ... and not cause casualties?

That's the question on Nick's mind on Friday's Grimm (9/8c, NBC) when he contemplates his duties as Monroe's best man. After all, once a Wesen woges in front of Nick (David Giuntoli), they're usually tipped off that he's a Grimm, and therefore, their mortal enemy.

PHOTOS: Memorable TV weddings

But after all of these years, we've never quite figured out how a Wesen can suss out Nick's true nature. Does he have a bad poker face? Does he smell funny? As usual, Wesen power couple Monroe (Silas Weir Mitchell) and Rosalee (Bree Turner) have all the answers:

Nick will certainly be making a fashion statement at the wedding!

Grimm airs Fridays at 9/8c on NBC.