promzilla
n. A high school girl who, while planning for her prom, becomes exceptionally selfish, difficult, and obnoxious.
Also Seen As
Etymology
Examples
2011
Inspired by films like High School Musical and the television show Glee, British teens are no longer content with the traditional end-of-term school disco and a plastic cup of lemonade to mark the end of their senior school years….

Such is the phenomenon's iron grip on the British teen's imagination that a new word has entered the lexicon: the Promzilla, a particular kind of prom-obsessed adolescent.
2009
Esposito remembered the late Father Melton and the priest’s claim to fame to get anyone into a college, in exchange for the opportunity to go to Prendie’s prom with a "promzilla."
—Linda Reilly, “Augustinian priests will be missed greatly at Bonner,” Delaware County Daily Times, May 10, 2009
2004 (earliest)
Count yourself lucky, Michelle!! If you didn't know what a Bridezilla was, this means you've never met one. LOL There is also Promzilla (impossible to please prom dress client).
—Sharon, “what to charge?,” alt.sewing, October 28, 2004