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ABC News' Mary Pflum reports:

The prom is every high school girl's dream, but showing up to the prom in a dress that another girl is wearing? That's the ultimate nightmare.

More and more girls are turning to social media to prevent that, said Betsy Fast, Web editor at Seventeen magazine.

The instant a girl picks a dress, they're now immediately posting a photo of it on Facebook or Twitter," Fast said, adding: "The girls are saying, 'This is my dress. You can't buy it! … It's mine!"

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At Ocean Township High School in Ocean Township, N.J., girls created a Facebook page to announce their prom gown choices in order to avoid copying each other's dresses.

Girls across the country feel the same way. Some of the cautionary messages posted online can be very strongly worded. One girl wrote: "I swear, if anyone steals my dress I will kill you," while another wrote: "Don't steal it or I'll cut you."

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Even celebrities - with their personal stylists and generous designers offering them couture fashion -have faced this dilemma.

Actress Anne Hathaway reportedly donned her second-choice dress for the Academy Awards this year after she learned that her "Les Miserables" co-star, Amanda Seyfried, was wearing a gown that was remarkably similar to the one she had originally planned to wear.

Other celebrities who've failed to avert this fashion catastrophe often find themselves featured in magazines that showcase the similar looks side-by-side to ask who wore it best.

The New Jersey teens are doing their best to avoid a similar outcome through their prom gown Facebook pages. Some of the girls said they've gotten good feedback about their dress choices, but others have reportedly been driven to tears by negative comments, or by too few people approving of their choice.