Justin Bieber is very sensitive about two things: sexy mom jokes, and Justin Timberlake comparisons. On a phone interview with Mojo of Mojo in the Morning, a Detroit radio show, Bieber threw a small tantrum when Mojo told him he thought he was listening to Justin Timberlake the first time he heard "Boyfriend."
Bieber then insulted Mojo's dead mom before abruptly hanging up the phone. You can listen to the interview below, edited for length.

The Insult:
http://soundcloud.com/gawker/bieberjt
The hang up:
http://soundcloud.com/gawker/bieberhangup-1

What a dick. I always hated that girl.

Haha, true that..

I can understand his reaction. Some people are very defensive about their mothers. If anything, I think the radio host made a mistake.

See the first clip about the mistake, yeah Justin handled it pretty well actually.
The Second clip, Justin's just being a dick. See to some people saying something like the interviewer said about a guy in the band One Direction liking older women, that would actually be funny; you laugh and reply something like, no my mom wouldn't do that, but to say something like "i'd worry about your mom bro". One, thats the douchebag jock response immature college kids give you, two, since where the fuck does Justin get off saying One Direction are "cool kids" hes roughly the same age as them and the fact that he tries to put himself as better is totally arrogant. Bieber = Immature ,this is why i don't like him, doesn't matter how many millions you have when you can't be a down to earth personality that people will respect.