fart sack 

The cover sheet on your mattress.

When doing the laudry today, don't forget to wash the fart sack.

fart sack by victorzulu November 29, 2010

sack of farts 

A fartsack. A sleeping bag.

Common use since World War II, maybe earlier.

After an evening of playing poker, everyone got into the sack of farts.

sack of farts by The Wog Whomper May 14, 2005

Sack O' Farts 

Calling someone this will gain you much street cred. You only call someone you absolutely despise. Like, with a burning passion.

Jack - i hate you billy, you ugly sack o' farts.
Billy - aw.
Ashley - ur so cool Jack.

Sack O' Farts by iCarlin July 5, 2016