Possibly the Biggest Monkey Wrench in My Life Gears.

Niggers.

[edit] Alright, originally just posted for comedic aspects, I'd just thought I'd expand a bit. It's not necessarily black people alone, but it's the particular blacks who act like animals all the time. They're rude, loud, obnoxious, arrogant, lazy, and irritating. They have no regard for other people's peace of mind, or even wholeness of body seeing as they raise the murder rate in Philly and other cities to absurd amounts. They grind my gears. So very very much.