This is the shortened way to say 'sorry' so you can forget 'soz'.
If the person you are saying S.O.W. to forgives you they can reply with S.O.K.
Guy 1: Why do you have my girlfriends underwear in your bedroom?
Guy 2: Oh, uh... Don't be mad but we had sex.
Guy 1: Wow. Thankyou for at least being honest.
Guy 2: Anyway, I am so S.O.W.
Guy 1: S.O.K. man, S.O.K.
Guy 2: So... cool beans?