Basically, it's a
combination of the words ballsack and butthole. It can be used in place of either words, but doesnt have the same
definitions as those words. It's used as an insult, with added
emphasize on butt or asshole and ballsack. It's like calling someone a ballsack and butthole at the same time.(NOTE- symonms for butthole and ballsack can also be emphasized or used) ex.- ass-sack. Another way it's used is as a curse, like damn.