Before its fake retirement tour, the McRib made intermittent and unannounced appearances on McDonald's menus nationwide.
It was a business strategy that the company built partly around the pricing for the pork scraps that make up the popular sandwich and partly to keep up the mystique of the dish.
Scarcity made consumers want McRib more. The sandwich gained an online following and even spawned a website that tracked sightings of the elusive limited-time offer.
Related: Taco Bell menu makes a surprise nationwide addition
The recipe kept the McRib popular and made it part of pop culture. The sandwich even received the ultimate pop culture tribute when it was parodied in an episode of "The Simpsons," during which Homer ignored his family to follow the Krusty Burger "Ribwich" around the country.
That episode perfectly parodied McDonald's (MCD) -) and laid bare the chain's marketing tactics. It showed both how a fast-food craze can build when a company manipulates supply and how absurdly far people will go to get something that has no real value beyond being somewhat enjoyable to eat.
And while McDonald's has no answer for Krusty Burger's short-lived "Whatcha-ma-carcass" sandwich, it does have another very limited item that has created a quiet craze.
It's not a secret-menu item because it's not actually something you can order. But it is, in many cases, a secret.
Image source: Justin Sullivan/Getty Images
McDonald's has a minty surprise
A secret-menu item is something not listed on the menu that customers can order or sometimes assemble themselves. In many cases, social media drives new recipes that can be made from existing ingredients with a sort of standard recipe.
That's how numerous Starbucks drinks, like Pink Drink, joined the chain's regular menu. People kept ordering it, baristas eventually learned how to make it and, led by popular demand, the product joined the official menu.
McDonald's has at times embraced its secret menu and has done some promotions around some of its better-known combinations.
Its biggest secret, however, may be that the chain offers White Buttermints, old-fashioned mints that you might know from your grandmother's house or that old-school steakhouse your oldest relative loves.
The 10-calorie treat appears on the chain's website. The mints are made of "sugar, corn syrup, partially hydrogenated soybean oil, sorbitol, butter, salt, peppermint oil, natural (dairy source) and artificial flavor, soy lecithin (emulsifier), TBHQ [an anti-oxidant], citric acid and sodium benzoate (preservatives)."
But finding the mints, which are randomly dropped into people's bags with no warning, is another thing entirely.
How do you find McDonald's Buttermints?
McDonald's offer of Buttermints, which come in a white plastic bag stamped with the company's logo and the "I'm Lovin' It" catchphrase, appears to be a low-key marketing campaign. The chain isn't hiding that they exist, but it also does not tell people where and when they may appear.
You can't order them and it's not clear when the chain places them in customers' bags. The McDonald's Buttermints have become a sort of legend where consumers aren't quite sure if they're real (they are).
They pop up just often enough to fuel the myth but not to entirely convince consumers they exist. Like a minty Loch Ness Monster or Bigfoot, their existence spreads stories and low-key drives interest in the chain.
It's a very odd promotion driven by scarcity — leading to the mints being sold on eBay — but it's so low-key that few people know about it.
Perhaps McDonald's has a long-term play here, where it brings the Buttermints out nationally, as it has done with Big Mac Sauce sold in Chicken McNuggets sauce containers and other limited-edition sauces driving customers to its restaurants.
For now, the mints remain a mystery and/or a delightful surprise in the rare cases when they appear in customers' orders.
McDonald's did not immediately return a request for comment on this story.
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