For prom night This product image courtesy of Lord & Taylor shows a dress by Decode 1.8. On prom night, though, the idea is to stand out on their own, making sure no one arrives to the big dance in the same dress. (AP) NEW YORK: Teenage girls largely live in a lookalike culture, wearing the same styles that they got in the same stores as their friends. On prom night, though, the idea is to stand out, making sure no one arrives to the big dance in the same outfit. To ensure their uniqueness — after they've shopped in faraway malls and tapped into store registries — girls are using social media to claim dibs on their dresses. A photo of Ashley McGowan's floor-length black gown is on the prom Facebook page for her school in suburban Somers, New York. She's relieved that only one other classmate has posted a black frock. “There's an unwritten rule: the moment you buy it, you post it so it's `your dress,”' explains McGowan. A fashion advice website, Fashism.com, has even launched a Facebook-based registry called “Got Dibs” that allows users to track who's wearing what to which high school event, and get feedback on their outfit before they wear it. Amy Avitable, senior vice president of marketing for Lord and amp; Taylor, which is partnering with Fashism.com on Got Dibs, says the project is a way to give girls an insurance policy that they'll have something special, while making sure they won't be second-guessing their outfit at the last minute. Here's how Got Dibs works: Girls can snap photos of themselves with the tags still on the dress and get instant advice on what shoes to wear, if the hemline is right or if the silhouette is flattering. The opinions of peers, whether they are best friends or online “friends” from around the country, are key to the tech-savvy, fashion-loving consumer, says Ashley Granata, Fashism.com's co-founder and chief marketing officer. But for prom-goers, it's the claim on a dress that matters most, she adds. “When I was a junior, a freshman came to my prom in the same dress. I was mortified,” Granata recalls. “It was a pink satin, princess cut with scalloped neckline. I thought it was interesting and beautiful. I was known to have individual sense of style _ and then this trendy girl shows up in the same thing. Now I can say it's really funny, but I was really upset about it.” Hollywood stars make a strong impression by owning their looks, and teenage girls want to do the same, says Jane Keltner de Valle, fashion news director of Teen Vogue.