Stana Katic Gets Goofy With a Mystery Man Behind the Scenes of Castle Season 5, Episode 8 (PHOTOS)

Stana Katic is currently hard at work playing Detective Kate Beckett on Castle, but that doesn't mean she can't goof off from time and time.

"Standing on a corner w this guy, trying to make some $. Anyone recognize him?" Stana wrote with the above picture of her and a guest star making crazy faces on set.  

When she didn't get a ton of responses, she followed up with another, more normal-looking photo. "How about now?" she asked her fans. 

We know! We know! It's none other than Lost alum Patrick Fischler, of course, who's set to guest star as an eyewitness named Leo Conrad in Episode 8, "After Hours."

Did you guess Stana's Castle co-star or did she have you stumped?