McDonald’s is exciting fans once again with the return of its popular Shamrock Shake, this time introducing Uncle O’Grimacey to celebrate the beloved drink. Limited-time Shamrock Shakes will hit participating restaurants across the U.S. on February 10, marking the beginning of the fast-food chain's annual 'Shamrock Season.' This year’s festivities also herald a reunion of McDonald’s infamous characters Grimace and Uncle O’Grimacey, who is making a nostalgic return from his advertising days in the '70s and '80s. 'Our long-standing tradition of the Shamrock Shake is a testament to the joy we bring to our customers,' said McDonald’s executive Michael Gonda. During this season, a portion of the proceeds—25 cents from each Shamrock Shake sold between February 10 and March 23—will benefit the Ronald McDonald House Charities (RMHC), with a goal to raise $5 million to support families with sick children. In addition to the shakes, McDonald’s is launching an Uncle O’Grimacy Merchandise Collection featuring items priced from $6 to $35. McDonald’s operates about 13,500 locations in the U.S., making the Shamrock Shake a seasonal favorite with a dedicated fanbase.