A HUGE MESS. Particularly personified by botches from BU stumbling down the street the morning after a huge porty, latte in one hand, blackberry in the other. A moss is a way of life.
Dude, that botch is a mosssssssssss. You totally should dump her.
Katya: wuddup girl
Yasmin: nm, just mossin
OR
Yasmin: -bumps really hard- o my bad
Katya: LIKE FKN MOSS!
OR
Katya: you wanna go have a bogie?
Yasmin: k lets moss in the gazibo