A B.O.S is a guy who pretends to be tough but is actually very sensitive if you can get past his emotionless facade.
Girl #2: Nope, Coty is a B.O.S!
Noun: That kid is a walking B.O. every weekend.
Adjective: I was completely B.O. last night, don't remember anything.
To find ultimate comfort in an environment.
Yo dude, my bo is so proper. I have an xbox, a sofa couch, beverages and food, plus I don't have to go to school or work.