Overly aggressive cyclists who ride fixed gear (single gear) road bikes and are generally employed as bike couriers. They have an elevated sense of importance and entitlement to the road and endanger everyone around them by running red lights, weaving between cars and getting irrate when anyone objects to their douchy ways. Their mortal enemy is the taxi driver, though they have a stong hatred of all motorists.
You can spot them at stop lights trying to impress everyone with their little balancing act, trying not to touch the ground with their feet (they will claim they do this to avoid unclipping their clip-in bike shoes). Their traditional garb includes 80's biker caps (they are far too cool to ever wear helmets), courier bags, bike shorts and ironic t-shirts.
If you see one approach at your own risk. They are known to fly off the handle or, at the very least, say something sarcastic. The best way to trap one is to lure them close with a tall boy of Stiegel of a bottle of Labatt 50 and then club them over the head with a U-lock.
Look at that Fixie la Douche who just cut off that old lady and then punched her car window for honking at him! What a prick!