Katie as a monster
Katie Ka-Boom is a minor fictional character in Warner Bros.' Animaniacs animated series. Katie is a teenage girl who lives with her family (Mom, Dad, and a younger brother named Tinker) in a suburban house somewhere in the United States (though her first appearance marked her hometown as being located in Pleasantville). Her main schtick is that she has a very bad temper, and when even the slightest thing goes wrong with her day, she suffers ridiculously overblown reactions (intended as a parody of the already-overblown stereotypical dramatics of teenage girls in fiction), usually a parody of Hulk. At times, she may literally explode with rage, and at other times she will transform into a monster. Her family has to suffer the brunt of these attacks; they seem resigned to suffer through such episodes, often donning protective gear or hiding in bunkers for safety. The family home usually suffers much damage before Katie's rage vanishes as if it had just started.
Originally only intended to make one appearance, which was in the "Animaniacs Stew" gag, Katie first appeared in the short "Katie Ka-Boo", alongside Chicken Boo, who was portraying her jock boyfriend named "C.B." In the end, upon learning the truth about him, she went ka-boom (Mad). She came back twenty or so episodes later in "The Driving Lesson" and appeared in a few other shorts, generally three minutes. Her odd affliction was never fully explained (the closest the series ever came was the catchphrase "I'M A TEENAGER!"), and most of the shorts stuck to the same idea, with only a slight change once and a while.
She appears less in the later seasons, most likely due to redundancy as well as her overly violent nature and frequent, monster-like appearances.
Voices
Laura Mooney voiced Katie. Rob Paulsen played her father parodying Jimmy Stewart, and her mother was voiced by Mary Gross.