To sab someone is to completely shut someone close to you out of your life wildly and unexpectedly. To "sab" someone means to block them on your phone, instagram, snapchat, and twitter. Considered a very wildcard move.
Jack: Aw dude, Alena just sabbed me
Ingrid: Whoa bro what does that mean you've known her forever
Jack: It means she blocked on every platform possible for no real reason.
