If you remember your color chart from school, those shades combine to make green. When the syrup is swirled together with the white ice cream, you get the Shamrock Shake's festive light green ...

They are green-colored shakes that appear ... creamy vanilla soft-serve blended with our minty Shamrock Shake syrup and topped with a whipped light cream," according to McDonald's.

Uncle O'Grimacey debuted in 1975, five years after the Shamrock Shake first hit the McDonald's menu. Shaped like Grimace, with a round body and short arms and legs, Uncle O'Grimacey is all green ...

By 1973, the shake was just a green-colored vanilla shake without the lemon-lime sherbet. A Shamrock Sundae was introduced in 1980, made with McDonald’s vanilla soft serve and topped with ...

By 1973, the shake was just a green-colored vanilla shake without the lemon-lime sherbet. There was a Shamrock Sundae. A Shamrock Sundae was introduced in 1980, made with McDonald’s vanilla ...