Move over, Shamrock Shake. A new frosty offering is coming to McDonald’s, and this one is bright purple and berry-flavored.

As its name suggests, the Grimace Shake is inspired by Grimace: the anthropomorphic purple blob that may or may not be a giant taste bud. It’s part of the Grimace Birthday Meal, which also includes fries and either a Big Mac or 10 Chicken McNuggets.

Grimace was introduced in 1971, which means he’s technically turning 52 this year. But the birthday party isn’t just for him: It’s also a way to honor the long legacy of people celebrating their own birthdays at McDonald’s.

“Our fans have amazing childhood memories of their birthdays at McDonald’s … and Grimace’s Birthday is all about paying homage to the amazing, fun moments we all share,” Tariq Hassan, chief marketing and customer experience officer at McDonald’s USA, said in a press release. “Grimace is the perfect lovable icon to have McDonald’s meet our fans at the intersection of nostalgia and culture.”

Grimace may seem lovable now, but he wasn’t always that way. The character’s original 1971 iteration was a four-armed milkshake thief named “Evil Grimace”—a backstory that helps shed light on why a seemingly innocuous fast food mascot has a name meaning, per Merriam-Webster, “a facial expression usually of disgust, disapproval, or pain.”

The Grimace Shake and the rest of the Grimace Birthday Meal will be available at participating restaurants in the U.S. starting Monday, June 12, and only while supplies last. There’s more to McDonald’s Grimace-centric birthday extravaganza, too, including a video game, apparel, and a donation campaign to Ronald McDonald House Charities. You can find out more about all the fun here.

This article was originally published on www.mentalfloss.com as A Purple ‘Grimace Shake’ Is Coming to McDonald’s.