Lululemon is joining many of your older coworkers in being tired of hearing about your dupe haul. The athleisure giant is suing Costco, alleging that the wholesale retailer is selling illegal knockoffs of its products, the Associated Press reported.The lawsuit is Lululemon’s most high-profile attempt at fighting back against Gen Z-driven “dupe culture.” Lulu says Costco is intentionally confusing shoppers by slapping its Kirkland brand on clothes that are thinly veiled copies of much more expensive Lulu items.Per the lawsuit:Costco’s $20 Hi-Tec Men’s Scuba Full Zip is a copy of Lulu’s Scuba jackets, which retail for over $100.Costco’s $10 Kirkland 5-Pocket Performance Pants are a duplicate of Lululemon’s $128 men’s ABC 5 Pocket Pants, which at least one person at your office is currently wearing.Lululemon also alleges that Costco stole its “Tidewater Teal” color. The brand is asking for a jury trial and wants Costco to stop selling the items in question.Can Lulu win? In April, the New York Times reviewed both Lululemon’s ABC pants and Costco’s version and found them to be suspiciously similar. But it’s typically hard for brands to prove that dupes are illegal, because US trademark law is often vague.Dupe or die. Thanks to TikTok trends and cost-conscious consumers, dupes have become so popular among younger shoppers that wearing them can be as much of a status symbol as owning the luxury original.—AEThis report was originally published by Morning Brew.This story was originally featured on Fortune.com