“Wait, bud light made a seltzer,” said Post Malone, standing in a convenience store in South Los Angeles. He frowned. “Wait, Bud Light made a seltzer,” he said again, quieter. “Wait, Bud Light made a seltzer?” Louder, now: “Wait, Bud Light made a seltzer!”

Post Malone covers the Spring/Summer issue of GQStyle. Click here to subscribe. Coat, $32,000, by Dior Men / Shirt, $595, by Tom Ford / Tie, $250, by Charvet / His own hat, by Stetson / His own watch, by Patek Philippe / Ring (on left hand), his own / Ring (on right hand, price upon request) by Jacob & Co.

It was five o'clock somewhere, but not in L.A., not that Post would have cared. Anyway, the store was fake: Post was on set, running lines for a commercial being filmed—amid military secrecy—for the Super Bowl. Post Malone has been hawking Bud Light since 2017, and drinking it for a good deal longer than that, and so Anheuser-Busch InBev had chosen him to help announce its newest product, Bud Light Seltzer: a watery beverage for people who find Bud Light too beery. Designers had converted an auto-body shop into a fake convenience store, which looked just like the real thing, except that all the brand names on the shelves were fictitious, besides Bud Light.

When Post was finally dismissed for a lunch break, he ambled out into the parking lot, which was surrounded by a fence that had been comprehensively tarped, for privacy. Post Malone is taller and more imposing than many people might expect, and he gained a few extra inches from the rich brown cowboy boots he was wearing. In conversation (as in song) he exudes a warm, stoney charisma. He found a seat on a cooler and dug into a pack of Camel cigarettes, paying little attention to the spread of cheesesteaks and fried-chicken sandwiches that had been brought in. The shoot was going well. “It's easy, because I don't have a lot of lines to memorize,” he said, smiling. He doesn't love delivering dialogue, especially in front of a group. “I'm shy,” he said.

Post Malone knows that he is not generally perceived as shy, and not just because he is one of the most popular musicians in the world. In the past few years, pretty much no one has been more consistent in making blockbuster hits: “Rockstar” and “Sunflower” and “Circles” and fistfuls more. Spotify named him the most streamed artist of 2019, and according to Nielsen, his 2019 album, Hollywood's Bleeding, was the most-listened-to album of the year, though it only arrived in September. Even as his music dominates the planet, Post Malone cultivates a gregarious image. He is only 24, and he has reacted to success with amusement and amazement while taking care to reassure fans that he hasn't lost his taste for cheap thrills, now that he can afford expensive ones. Along with Bud Light, his sponsors have included Crocs, which has created limited-edition Post-branded clogs, and Doritos, which used Post Malone to help publicize its Flamin' Hot Limón chips. (He renamed himself Post Limón for the occasion.) He is now a global celebrity, but Post Malone still acts like an interloper in this exclusive club, wandering through A-list parties with heavy eyelids and a sheepish smile.