(1) a woman who is so slutty that she is a semi-
prostitute, hence, semi-pro. Not to be confused with semi-rape.
(2) someone who excels in some field (e.g., pool) but falls
short of "professional" status.
(3) a male who "dusts the tip" of his male-friend to encourage him, if you know what I mean.
(4) refers to a feminine tone of voice that
men sometimes use when talking to girlfriends on the phone or when they feel nervous.