Don’t drag your heels if you want to join the ugly shoe trend.

If you thought the fashion world couldn’t get any weirder after luxury retailer Balenciaga copied Crocs’ signature rubber clogs, the comfort footwear brand’s newest style might put you over the edge. As reported by Independent, Crocs has released a high-heeled version of their rubber clog. And even though they’re not fashion-forward, they’re selling like hot cakes.

The 3.75-inch wedges come in two styles (gray with a pink insole and solid black) and retail for $55 — that is, if you can find them. USA Today has reported that the Crocs “stilettos” are sold out online, and resellers on Amazon have listed them for as much as $224. And that’s not all — the clodhoppers have clogged Twitter feeds for the last few days, and Instagram has more than a million posts using the hashtag #crocs.

And this isn’t the first time we’ve seen not-so-pretty fashion taking runways and social media feeds by storm. In the last few years, clunky designer shoes like Adidas’ Yeezy Boost 700’s and Balenciaga’s Triple S sneakers have caused an uproar among the fashion set who are split when it comes to determining whether or not the shoes are fun and expressive, or offensive and outlandish. Still, the $850 Balenciaga platform spike textured clogs are hard to come by as collectors and shoe aficionados are willing to pay through the roof to get their hands (and feet) on a pair. And the decidely unglamourous Birkenstock premiered at Paris Fashion Week last year and has popped up on the feet of celebrities like Kendall Jenner and Gigi Hadid.

What’s more, just as word of the new high heeled Crocs began to make waves, Balenciaga introduced a rubber-style stiletto of its own that is expected to sell out online before it even hits shelves.

Comfort is no doubt driving this trend: Market research firm NPD Group reports that sport leisure styles accounted for $9.6 billion of sales last year and running-inspired sneakers and casual athletic styles rose 39% and 24%, respectively.

And athleisure is so passable that Serena Williams got away with wearing sneakers underneath her Valentino gown to Prince Harry and Meghan Markle’s evening wedding reception. Whether you consider her choice ugly or practical, there’s actually a “trashion” trend that has fashionistas paying big bucks to wear clothes that look like garbage.

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Even some fans of these comfortable but ugly kicks confess that they know they’re not so stylish. Elizabeth S., a 30-year-old creative consultant who declined to give her last name, told Moneyish that she bought Birkenstocks because she needed comfortable shoes that she could slip on and off while working on set — she never intended to wear them when she wasn’t working. “They were so ugly, I figured I would never wear them again — and now I can’t take them off,” she said. “Deep down I know they’re hideous, but they’re so comfortable (that) I’ve been blinded.”

And fashion writer and creative consultant Melissa Magsaysay told Moneyish that the reason we keep seeing these types of shoes come back is because mass brands that feel more or less dusty, outdated or just plain nerdy have to evolve and remain relevant. “There’s been a perfect storm over the last five to seven years, coming off of the ‘norm core’ trend, where high-end houses and designers want to reinvent classics, and these older shoe brands need a cool refresh,” said Magsaysay.

“I love the fact that we’re celebrating what has traditionally been seen as ugly and playing up the styles, turning plain into something super interesting,” she added.