McDonald's has bottled their iconic 'Special Sauce' in preparation for a giveaway that will hand out 10,000 free bottles of the stuff to promote the launch of their new Big Macs.

"A new-Mac-Sandwich-sizes party needs epic party favors-like 10k bottles of Special Sauce. Tomorrow find out when/where you might get one!" McDonald's tweeted Tuesday.

The bottles are expected to be distributed at participating restaurants across the U.S. Thursday.

After announcing plans to both shrink and inflate their original iconic double-decker sandwich last year, the new Mac Jr. and Grand Mac launch Thursday.

For those with smaller appetites, the Mac Jr. is a Big Mac, minus the middle layer and second beef patty.

For bigger Mac attacks, the Grand Mac features bigger beef patties, at a weight of one-third of a pound.

The launch comes following a dip in sales over the last quarter. In the U.S., sales dipped by 1.3 percent compared to the same period in 2015. The drop is attributed to the strong results seen from their All-Day Breakfast program which launched in 2015.

The fast food giant is also hoping to resurrect its most iconic sandwich, particularly among Millennial consumers. According to an internal memo obtained by the Wall Street Journal last year, it's estimated that only one in five Millennials have ever tried the company's flagship product.

Meanwhile, in response to McDonald's tweet announcing the special sauce giveaway, one cheeky follower posted a photo of Kraft's Thousand Island dressing, with the message, "Sweet got mine!!"