About 20 web pages deep into research about a mint milkshake it hits you: those folks over at McDonald's are a real clever bunch. Newspaper articles, blog posts, online forums, videos, websites — all dedicated to the fast food giant's elusive seasonal confection, the Shamrock Shake. But why?

First introduced in 1970, the green-tinted milkshake was originally developed as a special offered during the month of March in honor of St. Patrick's Day. Since then it has become one of the company's most popular seasonal products. It is also credited by some as having paved the way for the success of other companies' seasonal beverages. Oh yeah, and it has basically skyrocketed into the stratosphere of cult phenomenon. Think of it as the drink equivalent of the McRib.

And it makes sense — it's a very tasty mint shake. But of course, there's more to it than that. Here's a look at what makes the Shamrock Shake a beloved cult classic.

1. Limited Supply Only. The three magic words — because nothing pushes a product better than an expiration date. Though it is supposedly only available during March, this year sightings were reported in the last week of February. What kind of erratic behavior does this get-it-while-you-can strategy inspire? I'll have four Shamrock Shakes for breakfast, please. What? I want to get it before they run out of the syrup!

2. The Hunt. Headlines for the first Shamrock Shake sightings of the season read like eyewitness accounts of seeing the Loch Ness Monster or the Abominable Snowman. The shake has a history of playing peek-a-boo during its already-limited one-month-only stint. In 2007, it was noticeably absent from the New York market — apparently branches vote by region as to whether or not they want to stock it. Suddenly milkshake becomes coveted treasure hunt prize. Fortunately, dedicated sites like Shamrockshake.com make the quest a whole lot easier.

3. Ripe for Debate. Don't mess with a sentimental food memory, man. Last year, loyalists were outraged when the company decided to "revamp" the flavor. Too much vanilla! Not enough mint! Someone even started a Facebook fan page protesting the reformulated recipe (granted it currently only has 63 members). Good news though, fans, early reports seem to suggest that this year's batch lives up to the hype.

4. The Nostalgia Factor. Just about anything with retro appeal does well these days and the Shamrock Shake is no exception. (Who here votes to bring Uncle O'Grimacey back?) It also doesn't hurt that the shake was featured in a viral video-worthy, oh-so-not-PC advertisement in the 1980's.

5. Many Imitators, One Original. Copycat Shamrock Shakes, "healthy" Shamrock Shakes, "adult" Shamrock Shakes. When McDonald's is a source of recipe inspiration, well, that's just badass. What is it they say about icons: Often imitated, never duplicated?

Related For the Love of the Shamrock Shake

Have you had your Shamrock Shake encounter yet this year? Weigh in on the minty madness in the comments below!