Craving a McDonald's lobster roll? More than likely, you're out of luck at your local McD's joint. In fact, there's a good chance you have never even heard about it.
All-day breakfast isn't the only idea fast food giant McDonald's is limiting to a select group of restaurants.
Depending on which of the country's more than 14,000 locations customers visit, they could see everything from buttermilk crispy chicken to bundt cakes on the menu at the chain's corporate and franchised branches.
When a restaurant is as big as the Golden Arches, it can't just hope a new item or feature like all-day breakfast works out. McDonald's uses small tests—like a current one with all-day breakfast in select San Diego-area restaurants—to see whether a new item has potential to be a hit or a flop.
The company also has a number of regional menu items meant to cater to local market preferences. As part of its turnaround efforts, McDonald's has pledged to localize its menu and marketing efforts to be more relevant to regional tastes.
Click ahead to see some of McDonald's most exclusive menu items.
—By CNBC's Katie Little
Updated 30 July 2015
Lobster roll
Menu bites: Pricier than most offerings at the Golden Arches, McDonald's Lobster Roll clocks in at $7.99.
Availability: Participating McDonald's locations in Maine, New Hampshire, Massachusetts, Rhode Island and Connecticut (excluding Fairfield County) are selling the seafood dish through mid-August.
Green teas
Menu bites: These green teas are sweetened with honey, garnished with lemon and poured over ice. They are available in two flavors: Classic Green Tea with Honey and a berry version.
Availability: These teas are being tested in Houston.
Shakin' flavor fries and McNuggets
Menu bites: Plain fries can be a thing of the past with this menu addition. Shakin' Flavor seasoning comes in three flavors (garlic parmesan, spicy buffalo or chipotle barbecue) and can be added to the chain's fries and McNuggets.
Availability: As of April, locations throughout Northern Nevada were offering the seasoning, and the chain planned to make it available in the San Francisco, Sacramento, Chico, and Fresno markets. The seasoning is a regional offer with no national plans for the item yet.
Buttermilk crispy chicken
Menu bites: McDonald's is testing a buttermilk crispy chicken, which consists of 100 percent white meat chicken breast marinated and battered with buttermilk and a spice blend. Customers can order the chicken in the Crispy Chicken Deluxe Sandwich, Premium McWrap, Snack Wrap or Premium Salad.
Availability: Earlier this year, 25 restaurants in Delaware or 20 restaurants in the Little Rock, Arkansas area were carrying the buttermilk chicken.
While McDonald's said in April it is premature to speculate about the test's outcome, chains often test items before deciding whether to launch them in more locations.
McDonald's could not be reached for comment about updated availability of its items it was testing or selling as regional offerings.
Bundt cake
Menu bites: This mini bundt cake comes in chocolate and cinnamon versions.
Availability: As of April, the cake was sold in select restaurants in the Los Angeles, San Diego, Florida, Houston and Atlanta regions as a regional dessert.
Mozzarella sticks
Menu bites: Who says you can't buy anything for a buck? A dollar buys customers three mozzarella sticks in pricey New York City.
Availability: As of April, the stickers were available at select locations in in New York, New Jersey, Connecticut, Atlanta, Florida, Philadelphia, Pittsburgh and St. Louis.
Fried apple pies
Menu bites: This fried creation differs from a separate nationwide baked apple pie item at the chain. McDonald's formerly had fried apple pieces on its national menu, but the item is now only available in a small number of markets.
Availability: A small number of restaurants in Florida, Hawaii and the Los Angeles market had this regional offer as of April.
Fresh baked muffins
Menu bites: These muffins by Quaker come in blueberry, double chocolate and orange cranberry flavors. An emphasis on "freshness" is a common theme at the Golden Arches these days as McDonald's tries to revamp its consumer brand perception.
Availability: Only select restaurants in Michigan, Indiana and Chicago offered the muffins as of April. Available flavors also may vary by region.
Petite pastries
Menu bites: McDonald's offers these small pastries in raspberry and cinnamon cream cheese flavors.
Availability: Select locations in the Los Angeles and San Diego areas offered the regional item as of April.
Cookies and crème frappe
Menu bites: This McCafe frappe is flavored combined with the cookies and cream flavors and chocolate cookie crumbles, topped with whipped cream and a sprinkling of more chocolate cookie crumbles.
Availability: This regional limited time offer was rolling out to select restaurants in the Indianapolis, Pittsburgh and Raleigh regions as of April.
Don't live there? You could be in luck still. In the future, the frappe could be available in additional markets, wrote Terri Hickey, a McDonald's spokeswoman, in an April email.