adj. speech or behavior that is over the top, unhinged, self-destructive, or a threat to others.
Condition may be temporary (e.g. Dad went all batshit crazy on me when he saw the cell phone bill) or prolonged (Adolph Hitler was a batshit crazy megalomaniac responsible for the deaths of millions in 20th-century Europe.)
see [batshit], [batshit fucking insane]