A name commonly used by students at the University of Wisconsin - Platteville for their school. P-Vegas is short for Platteville-Vegas. This term is often used ironically due to the fact that Platteville, Wisconsin is a great city in the middle of Wisconsin farmland just as Vegas is in the middle of a desert.
Person 1: Hey bro, are you coming down to P-Vegas for my birthday this weekend?
Person 2: Nah, I'm stuck here in Madison.
Person 1: So where are you partying this Spring Break?
Person 2: I'm partying here in P-Vegas!