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.