Courtesy Jack In The Box

You've heard of combining milk and cookies, bacon and eggs.  Now you can get three out of four of those items together, in one creamy shake.

It's the bacon milkshake, and it's the brainchild of the Jack in the Box fast-food chain.

The shake, taking the concept of fast food and buy one, get one free to a whole new level, gives a meaty element to the normally dairy-laden treat.  Sadly for true carnivores, however, it is said to contain only bacon-flavored syrup, not the real thing.

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Still, according to the to the Jack in the Box website, a regular-size  16 ounce  bacon shake weighs in at a hefty 773 calories and 40 grams of fat, while a 24 ounce  large option packs 1,081 calories and 54 grams of fat, nearly an entire day's allowance.

The bacon milkshake is part of the 2,200-store, San Diego-based chain's new " Marry Bacon" ad campaign that asks, "Love Bacon? Marry It," and encourages visitors to the chain's website to "Make a Bacon Baby."

In addition to the calories, a regular-size  milkshake costs $2.90 after tax.  But don't expect to just walk in or drive up to your local Jack in the Box and see the new item on the menu.

"The shake is not listed on our menus in the restaurants, so it's more of a 'secret item' that people can order. Each restaurant is getting a very limited quantity, so we don't know how long they will last," a Jack in the Box spokesperson told the Huffington Post.

Indeed, the chain is advertising the new shake with a disclaimer that says the drink is "as limited as limited can be" and "might disappear."

While Jack in the Box restaurants are  found only in 19 states, most of the restaurants are open 18 to 24 hours a day, plenty of time in which to track down and slurp down the meat-flavored treat.