If you're feeling nervous and agitated, you're in a tizzy. If you dislike public speaking, you might be in a tizzy about an upcoming presentation you're giving at school.
The noun tizzy can be positive or negative. So you may get into a tizzy about a big party you're throwing next week, feeling anxious and excited simultaneously. But you can also be in a tizzy about your terrible grade on a math test. Experts aren't sure about the origin of this informal American word, although they know it's been in use since the 1930s.