look up any word, like bukkake:
 
1.
a large sac of marijuana.
"Let me buy that fat sac off you."
by tha dude December 17, 2006
 
2.
Its a sac of fat that is someplace on your body you don't want it
you're a fatsac
by The gr 6 class of holy name May 28, 2011
 
3.
A water filled bag used to add ballast to boats in order to produce a larger wake. This enables wakeboarders to get more air.
The Fat Sac ads up to 600 pounds of weight to your boat.
by TT September 12, 2003
 
4.
An exceptionally large scrotum.
DAMN!!!!! DAT fool's got a FAT SAC!!!!
by fun-o-bunz August 13, 2003