We may not all be Irish but that doesn't stop us from celebrating St. Patrick's Day. According to the National Retail Federation over half of Americans will take part in the holiday. That's 122 million people going to parties, decorating with four-leaf clovers, drinking green beer, and eating green mashed potatoes. Total spending for the green day is expected to reach $4.14 billion! My favorite St. Patrick's Day treat is the McDonald's Shamrock Shake. To learn more about the famous shake, including history, old ads, and nutritional facts (I'll warn you, you may not really want to know about that), check out the Ultimate McDonald's Shamrock Shake Guide. If you want to get yourself some of the minty goodness today, check out the Shamrock Shake Locator to see if they have been sighted in your area.