Zach kept trying to disguise it by raising both his hands to his hair constantly.
In the last minute it looks like he just gave in.
It's kind of creepy, but I think the producers are going to purposely pan in on them, especially the guys when they're in the shower now. I had never seen the camera pan in so close to one of them and it's like they zoomed in on him so they could catch it if he did.
what is life 
