1. rude slang To become uncontrollably or intensely irrational; to act in a wildly irrational manner. The drivers in this country seem to go completely batshit crazy if there's even a little bit of snow on the ground. If they get too much sugar, the kids start going batshit crazy and start running around the house screaming.

2. rude slang To become wildly or uncontrollably angry. My parents went totally batshit crazy when they found out I'd wrecked the car! Now, don't go batshit crazy or anything, but I've decided to move to Canada.

3. rude slang To become extremely excited or enthusiastic (about something). I've never understood that pop star's popularity, but kids just go batshit crazy for her music.