[1] : WordNet (r) 2.0

pop off
     v 1: leave quickly
     2: die; "the old man finally kicked the bucket" syn: kick the
        bucket, cash in one's chips, buy the farm, conk, give-up
        the ghost, drop dead, choke, croak, snuff it
see also:
kick the bucket cash in one's chips buy the farm conk give-up the ghost drop dead 
choke croak snuff it 

[2] : Moby Thesaurus II by Grady Ward, 1.0

32 moby thesaurus words for "pop off":
   blow, buy it, cash in, check in, check out, croak, die, drop off,
   exit, get away, get off, go, go west, have it, kick in, kick off,
   kick the bucket, knock off, leave, pass, pass away, pass out,
   peg out, perish, pipe off, pull out, retire, run along, shove off,
   step off, succumb, take off

Blow Off >> B Words
Blow Off, definition of term: Blow Off
blow+off_pag1.html

Bite Off >> B Words
Bite Off, definition of term: Bite Off
bite+off_pag1.html

Better Off >> B Words
Better Off, definition of term: Better Off
better+off_pag1.html

Bear Off >> B Words
Bear Off, definition of term: Bear Off
bear+off_pag1.html

Back Off >> B Words
Back Off, definition of term: Back Off
back+off_pag1.html