Trent Reznor isn't known for his sunny disposition, at this year's Reading Festival he publicly criticised the festival and national treasures, Biffy Clyro - before he performed at the event. Reznor is traditionally a prickly individual, never afraid to share his opinions or smash up a stage if things aren't to his liking. Check out some of his grumpiest, most outspoken and angriest moments of all time here.