Grimace, the fuzzy, purple McDonald’s mascot, turned 52 years old on June 12. The fast-food company has spun this non-milestone birthday into its biggest celebration of the year, and in turn made Grimace one of summer’s biggest social-media stars.⁠ ⁠ TikTok is teeming with viral videos where customers try the Grimace Milkshake, a berry-flavored beverage concocted by McDonald’s as part of a special Grimace Meal. But there’s a twist: Young people are pretending to die in violent and strange ways at the hands of the drink—a play on Grimace’s villainous origin story.⁠ ⁠ The company had been going for nostalgia with the campaign, according to Jennifer “JJ” Healan, vice president of marketing, brand, content and culture for McDonald’s in the U.S. “Our fans truly brought their version of Grimace’s birthday through the lens of the shake in really unexpected and fun ways, and so we’re here for it,” she said.⁠ ⁠ Since the “Grimace’s Birthday” campaign was launched last month, videos with the has...