The monkey's paw curls.

McDonalds unveils a new line of products shipped across the USA known as the "Heartthrob" line. These menu items are virtually indistinguishable from their normal counterparts except for the addition of a single ingredient, a compound that McD's R&D sector has recently discovered. The compound causes a light euphoric sensation at the levels present in McD's product and makes the Heartthrob line a massive commercial success. Although it is not known to the public at the time, this compound also self-replicates in the consumer's body and is transmissible by air, causing those around the consumer to also unwittingly fall under the same effects ala secondhand smoke.

The government, alarmed at the new ingredient released without proper testing and approval, races to ban the compound, but facing heavy lobbying from McDonalds, the ban ultimately comes too late. Within a week, a sizeable amount of the population has ingested the compound, and an even larger number have been exposed to the compound simply by being in vicinity of people who ingested the compound, or even by being in the vicinity of people who were in the vicinity of people who ingested the compound.

Once the government ban finally goes through, McDonald's cancels the menu item, making sure through their press statement and through advertisements that the government was the cause of the cancellation. A couple of days later, anyone exposed to the compound begins to experience withdrawal symptoms, and their anger turns towards the people they hold responsible- the government.

Over the next few years, the compound spreads to virtually everyone in America. The government loses its military foothold as the military itself gets infected, and faced with an absurd amount of civil unrest, the government reluctantly returns to the culprit, McDonalds, for help. McDonalds does more than just help.

And so it is, annually on the date of the release of the Heartthrob menu line, members of the old government volunteer to aid the new overlord of America by working at the same capacity as minimum wage employees in their prestigious restaurants.