Ever been involved in a hookup?
It's different in college. This might get a little graphic, so you don't have to read any further.
But basically a hookup is pretty much hooking up with some anonymous person on campus, and basically just fondling with body parts and getting funky funky without seeing that person the next day...or ever.
The problem with this is that it's easy to get emotionally attached, basically a "catch feeling."
Personally, I can't recommend this to anyone really...it's too easy to become emotionally attached. You should always stick to your true friends, but experimentation can sometimes have dire consequences. I think 3/4 college student goes through this, so I guess it isn't anything too new.