Snooki Blush refers to the episode of Jersey Shore where Snooki gets punched in the face. When she was punched, it left quite a bruise, adding color to her face, much like blush would. It is primarily used to describe the act of being punched in the face, or describing someone who was punched in the face.
Joe: Your mother is a whore.
Tom: Watch it, or ill give you some Snooki Blush.
Jack: Hey Kevin, did you hear what happened to Joe?
Kevin: Heh yeah. Tom gave him some nasty Snooki Blush.