Acting in a generally insane manner; Tom Cruise.

One step beyond just plain crazy. It is usually a temporary thing...sparked by something unexpected, or just really awful.

Crazy to a degree bordering on complete insanity. The state in which one makes decisions which make the exact opposite of sense.

See also: bat-shit

adj. (slang): A combined state of mental agitation and physical volatility. It's use may provide warning that the individual it describes has lost all self-control and cannot be reasoned with. Can refer to either a chronic or temporary condition.

The highest level of crazy, which causes people to outrageous things that automatically attract media attention.