McDonald's Shamrock Shake to Be Joined by Oreo Shamrock McFlurry It's nearly time for Shamrock Shake season. This year is the St. Patrick's Day-themed item's 50th anniversary. The famous shake will be available nationwide starting February 19. For 2020, McDonald's is introducing another St. Patrick's Day-themed drink, the Oreo Shamrock McFlurry. The move comes after the chain served an Oreo Mint McFlurry in limited locations last fall. Combined with "shamrock flavor," the McFlurry adds oreo pieces to vanilla soft serve ice cream. Just like the regular Shamrock Shake, it is expected to be available for a limited time.