squirrelshit
Completely insane. Related to the term "nuts" (meaning the same thing) in the same way that "apeshit" is related to "bananas" and "batshit" is related to "batty." It is unknown whether the offensive terms were dysphemisms of the innocuous terms or the innocuous terms euphemisms of the offensive terms. Excepting "apeshit," all of these terms (including "bananas") have the same meaning, that is, "crazy."
My girlfriend went totally squirrelshit when she found out I had crabs.