A sudden, seemingly reasonless burst of anger. Typically from a woman. Though a man can be the culprit, if particularly feminine. Men usually have reason for their temper tantrums.
Can consist of, but not limited to: yelling, screaming, slapping, hitting, foaming at the mouth, bewilderment, and/or diarrhea.
That last symptom can be of either the victim or the batshitter, the second to last is limited only to the victim.
Past tense is 'batshat' since 'batshitted' is just plain improper, and 'batshatted' is a double past tense.
"We were just sitting on the couch watching a movie with, all of a sudden she had an unprovoked batshit".
"Yeah mine's done that before, must've breathed wrong".
"Oh my bad".
"It's okay, it happens".