What is the meaning of the song "Nice Guys" by nigahiga and kevjumba?

It's that most girls want guys who can be the "tough guy" in a way, according to stereotype. Therefore, in this song, they think that since nice guys don't last as boyfriends, husbands, etc., they will be the "bad guy" who will get all the girls because girls (especially the one they are changing for) will like them. They really like the girl and don't want to change, but feel they have to. In this song, they kind of go over board in trying to be the "bad guy" and push the girl they like away from them. If you saw either music video you will probably understand the meaning of the song better.