The bed/couch/etc. where you have been sleeping, lounging, eating, playing video games, watching t.v. etc. for more thana couple of days in a row, without showering or going out. You only get up to use the restroom, get something to eat/drink and then flop back down. This type of situation usually means that there is a definate funk surrounding you that smells something like a fart.
Yo Man, roll outta that fart sack and lets go get some grub!! Shheeeeiit, you been layin up in this fart sack for the past WEEK!!! C'mon, lets roll.
The type if fart that emonates up through you butt crack while you are sitting down. It pauses monentarily and then lightly fluffs past your ball sack. The fart is complete...