To pass out due to drinking before midnight, generally causing this person to miss out on something cool or extremely fun happening later in the night.
verb: To "ass out" is akin to "passing out," although it generally means going to sleep in a haphazard manner as opposed to becoming unconscious. For instance, after a long night of partying, one will generally ass out as soon as they get home, often falling asleep with their clothes still on or maybe on a couch.