Here is urban dictionary's definition of a bitch fit:
-When a person, usually a female is angry and upset about something and starts whining/crying/yelling/screaming/throwing things when things don't go their way.
-Basically its going all PMSing and Godzilla like.
-Also can just be "BF" if you can't curse in front of certain people.
-Made famous by the Wayans Brothers comedy "White Chicks."