Justin Bieber's fans have drawn the line -- it's ok to walk the cold streets of London shirtless, it's ok to smoke dope, but show up 2 hours late for a concert and they'll turn on him like wild animals.
Justin's concert in London Monday was slated to start at 8:30 PM ... but he didn't take the stage until 10:30 PM -- and a very young and pissed off crowd roundly booed his skinny ass.
Particularly irritating ... most of his fans have a curfew, which put them in a bad position.
Bieber tried to defend his lateness by tweeting he was actually only 40 minutes late because the opening acts were always scheduled to last more than an hour
