So two things that I don't think could be any more polar opposites are Slipknot and Justin Bieber.  Well when you mashup Justin Bieber's 'Baby' with the vocals from Slipknot's 'Psychosocial' you get one unlikely mashup that sounds surprisingly awesome.

It's the mashup you never wanted to hear, and now you can't get it out of your head.  I'm a big fan of mashups so if you ever come across any cool ones don't hesitate to send them my way.  Especially if they are as good as this one. The beginning is a bit off putting but wait until the chorus!

Enjoy the musical masterpiece you never wanted to hear!