Maybe you can't kiss the Blarney Stone, but you can get a minty delight to celebrate St. Patrick's Day. It's time for McDonald's bright-green Shamrock Shake, only available around St. Patrick's Day each year. It's hard to believe that this beverage has a cult following, that rivals that of¬"The Rocky Horror Picture Show" (though possibly not McDonald's other fan-favorite seasonal menu item, the McRib). The shake counts over 21,000 fans on its unofficial Facebook page and famous fans like Jimmy Fallon have paid public tribute to its allure.¬The shake's availability varies from franchise to franchise, so Shamrock cultists have crowdsourced a Shamrock Shake locator on the web. One more reason to hear their current catch phrase - "I'm Lovin' It".

Want to know what all the fuss is about? Check out this vintage Shamrock Shake commercial from 1983. It may hold the answer:

I think it's the free magical leprechaun hat. I want one of those leprechaun hats with my shake. I don't ask for much!