When someone slouches over for a long period of time, they have two or three lines appear on their stomach making them look as if they have a six-pack (at a quick glance, woah).
Slouch-pack, more like! When do you do anything physical?!
Six pack abs only attained by slouching/hunching over, making it seem as though someone is stronger than they really are.
Person 1:"Dude! That guy is ripped in his profile picture!"
Person 2:"No, he just has a slouch-pack."
"Hey, quit trying to look cool with your slouch-pack"