As an adjective, any sort of typically degenerate behavior. Usually said in the context of sexual promiscuity or alcohol related misconduct.
Celeste: I woke up naked and didn't even know which dorm I was in.
Haley: Omg Celeste stop being so college!
George: It's Wednesday night, so obviously we're hitting the bars and getting blackout.
Adam: How college of you!
Hannah: IM SO DRUNK
Celeste: COLLEGE!
Another version of school (pain in the ***) but it actually affects your future career.
Man, why didn't we take college before we went to school?
A place where you go and spend lots of money, ultimately to waste time on Urban Dictionary when you're supposed to be writing a case study on Women in Management.
Transgender Uncle: How's college treating ya?
Me: Not as well as it treated you.