Well, it looks like just a regular t-shirt collar in this one:
...but I suppose a quick look around the Gap couldn't hurt; thanks. It seems like it'd be a commercially-available shirt, because they're doing some funky things on the show with it, and if it was readily-available, I wanted to get one for one of my pals as a gag.
I found one exactly like it made by Arizona company on clearance at JC Pennys in February. While I doubt it's the one they used on the show (it'd have been about 3 or 4 years old by that time), it's exact as far as I can tell.
Obviously, JC Penny doesn't sell them anymore, but it's certainly the most recently available version of it, so you might be able to find it at an outlet store or on the 'bay pretty easily.
Obviously, JC Penny doesn't sell them anymore, but it's certainly the most recently available version of it, so you might be able to find it at an outlet store or on the 'bay pretty easily.