Someone you do not want to waste time with. Either they've had too little sleep, too much to drink, or they get a significant other.

One who has a mania for music.

when something has gone completely wrong

A phrase initiated by the esteemed Karl Rove to represent anything, and anyone that is cheaper to replace than repair. In other words, anything that is, or anyone who does something irrefutably stupid, annoying, or out of place.

To be dumped. Taken from the Real World: Austin.

To be beaten so bad that you have to goto intensive care. Derives from a car being "written off".

A stupid person.