The song repeats the phrase 'I know you want it' a lot. In other words, according to Mr Thicke or whoever wrote this, it seems that although a woman is saying 'no' she really means 'yes'. Another line in the song is 'I'll give you something big enough to tear your ass in two'.
Radio One may bleep out the offending lyrics, but that will only increase people's curiosity to look for the uncensored version, which can be easily found online.
This song advocates criminal acts, and the music industry should be held accountable. I shall finish this post with the awesome parody by a group of Australian students.