1. To be or become wild, restless, irrational, or crazy; to act in such a way. The drivers in this country seem to go completely bonkers if there's even a little bit of snow on the ground. Don't give the kids too much sugar or they'll end up going bonkers! We thought taking our family vacation in a tiny cottage out in the country would be a nice break from city life, but we all went a bit bonkers after a few days.

2. To be or become very angry or upset. My parents went bonkers when they found out I'd taken the car without asking. Now, don't go bonkers or anything, but I've decided to move to Canada.

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