After the Leviathans escaped Purgatory, they began their plan of consuming the entire human race. One of the Leviathans, Dr. Gaines, set up a strategy of distributing a hamburger laced with an unknown substance that was intended to turn humans into complacent, overweight drones, ready for slaughter.
This type of hamburger was mainly sold at Biggerson's throughout America for a limited time. Customers who ate the burger found it very delicious, and demand for it grew rapidly. However, customers also became very hungry, on top of behaving in a complacent manner.
Eventually, a man named Gerald Browder was driven to cannibalism and began feeding on actual humans. When Sam and Bobby did an autopsy on Gerald's corpse, they found his organs were swimming in gray goo, which they later found was a substance put into the hamburger.
Because of what Gerald did under the effects of the hamburger, the incident hit the newspapers. Dick Roman chose to shut down the project as a result, and punished Dr. Gaines by forcing him to eat himself.