Describing a person in a group who at any moment in time will draw their phone out the fastest just to instagram the picture first
Bob: wow what a nice sunset
Jill: ya, let me take my-
Bryan: LET ME INSTA DAT SHIT FIRST!
Bob: damn bro you are instahappy. Calm yourself
Bryan: I saw it first #duhh
2 or more women that are friends or sisters that have sex with the same dude continuously so the guy refers to them as "slisters" (slut sisters )
Bro1: dude see those chicks over there?
Bro2: ya man
Bro1: they're slisters
Bro1: Im fuckin em both.. slut sisters
Bro2: oh nice! *high five*