McDonald's is leaning on customers' nostalgia for its McDonaldland characters to spur sales of its Shamrock Shake. The company said Tuesday that Grimace will reunite with his Iris

Despite his hiatus, the green, furry icon was never forgotten. Uncle O’Grimacey earned his own merch line, called the Uncle O'Grimacey collection, which includes Shamrock Season pins, a crewneck and, even, a plain white tee that says “Who’s your uncle?” alongside an image of the uncle himself.