The number of times your ass leaves or touches a seat for any given activity. Useful for evaluating the relative effort required between two activities, especially when one activity involves someone else doing the work.
If I eat the cold pizza in the fridge, that's an ass factor of 2 (ass leaves couch, get pizza, ass touches seat), whereas going to Burger King is an ass factor of 4 (ass leaves couch, touches car seat, leaves car seat and then touches couch).
If I get up and get a beer, that's an ass fact or of 2. If you get it for me, that's an ass factor of 0.