McDonald’s is bringing back its beloved Shamrock Shake with the help of an old friend. The minty green milkshake will return to restaurants on Monday, Feb. 10 — and the chain’s Uncle O’Grimacey character is returning after a decades-long hiatus to help kick off the annual “Shamrock Season.”

Have you ever wondered what gives McDonald's iconic Shamrock Shake that distinct green color? You may not be surprised by the answer.

Grimace and Uncle O’Grimacey are welcoming the Shamrock Shake back to restaurants nationwide on Monday, Feb. 10

McDonald's brings back Uncle O'Grimacey, the beloved green mascot, to celebrate the return of the Shamrock Shake.

From the various flavors that have been available to the struggles of unveiling it nationwide, here's what you should know about McD's minty green shake.

The beloved Shamrock Shake is coming back to McDonald's, along with a McDonald's character no one's seen since the 1980's: Uncle O'Grimacey.

Shamrock Shakes are back at the restaurants. The Oreo Shamrock McFlurry has made a limited time return, as well. Start the day smarter. Get all the news you need in your inbox each morning. Shamrock Shakes sales do some good.