Beauty Queen Butcher(1991)

Phyllis Loden is an overweight shy nerd who is relentlessly picked on by the more popular girls. This year's Slivis Slough Queen Beauty Pageant is fast approaching and Muffy Fairlane is a lock to win. However, Muffy doesn't want any of her friends to come in last so she enters Phyllis in the pageant. The plan works and also provides the girls with some opportunities to embarrass Phyllis in front of the whole school. As if that isn't bad enough Elizabeth McKay thinks she could've won it all if it wasn't for her allergic reaction the Phyllis' cat. So the girls decide to dispose of the feline. That turns out to be the final straw which sends Phyllis on a murderous rampage to eliminate the beauty queens one by one.