McDonald’s is celebrating Grimace this month. The fast food giant is introducing the Grimace Birthday shake, a purple, berry flavored treat to celebrate the character’s 51st birthday. You can get it solo, or as part of the Grimace Birthday Meal, which also includes medium fries and a 10 piece chicken McNugget or a Big Mac. It rolls out on June 20th along with new Cheesy Jalapeño Bacon Quarter Pounder with Cheese.