According to my Kenkyusha Shin Waei Chu Jiten, sukebe, or sukebee to be exact, means "lecher, lustful etc." and I agree. Sukebee means someone whose mind is sort of obsessed with sexual desire.
Playboys can also be obsessed with sexual desire, but it's not necessarily the same. According to my Oxford Dictionary it even says that it's a "rich man who spends his time enjoying himself" and mentioned nothing about liking women. Anyway, I think the word "playboy" gives you the impression of a dandy guy who knows how to escort ladies, except that he goes from one lady to another.
On the other hand, sukebee can be true to his one and only lady and yet he is thinking about sex all the time instead of trying to escort her or act elegantly. Sukebee has nothing to do with being handsome or stylish. Quite the contrary, in fact.
But after all, aren't we adults and adolescents all sukebee to a certain extent? So I would call it "teasing" rather than "insulting".
On a related note, most if not all Japanese people know the English word "playboy" but not many know words like "lech" or "lust" hence the explanation from your friend.