comes from the words "sorrority" and "prostitute." A young coed who pledges a sorrority and frequents frat parties, subsequently fornicating with many of them at a time.
Rick: "Man, I'm gonna go spit some game at that Alpha Beta Gamma...she is smoking hot."
Gary: "Dude, you don't want that. She's a bonefied sorrostitute. She's banged Tony, Mike, Dave, Nick & Tim at the same time, John..."