look up any word, like donkey punch:
 
1.
To fall asleep
Jeff, I am pretty tired. Can I sack out at your place tonight?
by johnls7424 January 25, 2012
 
2.
To go to bed.
I'm so dead tired. I can't wait to go home and sack-out.
by 7h0rn3 May 14, 2009