Apparently Justin Bieber, 18, is not a fan of The Black Keys' drummer, Patrick Carney. He seems to have set Justin off when he threw some shade at him on the Grammys red carpet Sunday, and based on Justin's reaction tweet, he's ready to throw down! more
Source:
http://entertainment.newsplurk.com/2013/02/is-justin-bieber-capable-of-slapping.html