The reaction to Harry Styles’s semi-sheer Gucci Met Gala outfit this year was mixed, but onlookers agreed on one thing: His single pearl earring was the accessory of the night. One-sided and off-balance, the single dangly earring is back. In the mid-’80s, it was sported by Rob Lowe in St. Elmo’s Fire, Bob Dylan at Live Aid, and George Michael pretty much everywhere. It even traveled into the ’90s in the form of Michael Jordan’s gold hoop. And now it’s reemerged. “Old Town Road” rapper Lil Nas X often performs in a hanging-cross earring. Flamboyant reggaeton singer Bad Bunny regularly wears an even longer one. Onscreen, Julio Torres sports a singly dangly and blue hair in Los Espookys. And in the trailer for American Horror Story: 1984, Cody Fern smolders in impossibly short shorts, a tight tank, and a lopsided piercing. The look isn’t confined to celebrities. Per one meme, the earring is in favor among “gays, musicians, artists, goths, skaters, and bisexuals,” or, as one earring-wearer phrased it, “creative souls in Bushwick and the East Village.” Like the skinny mustache, it’s an accessory that plays with gender tropes — a traditionally feminine applique that now spans a full r...