Another idiom that means the same as.."Gone bananas"....but taking it to a much higher level.

A state of anger and rage that produces behavior more closely resembling that of an enraged ape than a human.

From the habit of enraged apes of flinging their own feces at their object of anger (if you haven't experienced this phenomenon first hand consider yourself blessed).

adj. An undignified loss of control, as in "To go apeshit".

Extreme anger or a state of insanity stemming from anger. When someone goes fucking crazy.

To loose all sense of reason. Said apeshitter will often start to speak in some strange language where the only recognisable words are "fuck" and other curses.

To go completely off the deep end; succumb to extreme rage.

Really really really angry or pissed off!
Its not uncommon to go apeshit:
When the dog shits in yer slippers.
When your husband sleeps with your sister.
When some ugly bollocks grab asses you.
When cars purposefully splash you on your way to an interview in your lovely white suit.
Most things the average family does.

to lose all self-control, and in general go fucking crazy