Stepson is Obscene

Well, my 15-year-old stepson apparently doesn't have any parental supervision at all.  Besides the language he uses on his facebook page (swearing a lot, calling his sister names like "w*ore"), he recorded a song to the song, "Wheels on the Bus" but made his own version of it and he's posted it all over facebook.  His version talks about what promiscuous kids do on the bus - that's the best way I can word it without offending anybody.  It's obscene and disgusting.  My husband is working this weekend or else I'd have him listening to it this second.  I'm so upset that I'm shaking.

I don't know if his mother is clueless or if she just has no control over him at all (or doesn't think she has to).  Giving past history where she never disciplined him, my best guess is she still lets him do whatever he pleases without consequences.  That'd be true to form for her - we were the disciplinarians (and he hates us for it because his mom used it to make her the favorite and us the bad guys) and she was/is Disney Mom. 

She's a pathetic excuse for a mother.