used when geting out of a seat, with intention of returning to the same seat at a later time, informing those sitting near you to save that seat, and keep thier butts out of it. calling this designates your seat as "taken"
*when leaving seat* "ass back"
*when returning and seat is taken "dude, get up i called ass back"
*when someone tries to take seat, a friend may say* "you can't sit there, rachel called ass back.