has 2 meaning that are total opposites:
1) someone/thing that is so ugly that you have to turn your head so quickly away from it, that you break your neck
2) someone/thing that is the shiznit and you turn yo head so quickly to look that you break your neck...
*not literally* :P lol
1) what the fuck was that, that hoe all rubbing up on me, shit she was a mutha fucking breakneck
2) dam girl your so breakneck