When a girl drops to her knees to give a blow job, while at the same time fingering herself. This is either to turn the guy on more or due to her horniness. Typically occurs in a restroom or frat party. Phrase originated years ago at BU and has since spread through Boston, NYC, and DC.
Fratter 1: Dude don't go into the bathroom
Fratter 2: Why not bro?
Fratter 1: Some dick grabber is in there giving grace to your roomate.
Fratter 2: Sorostitutes are awesome!