The first thing that popped into my head was they will be filling these burgers with graphese nano partickes - that react to 5G frequency... it basically turns the particles into antennas.
Now, what they receive, and what the effect of that is, is anyones guess... but back in 2017 I read an interesting article regarding zombie ants - that become hosts to fungal spores, that take the bodies of the ants over, causing the usual ground dwelling ant to climb into a tree, so, when the fungus fruit bursts the spores are spread further afield.
I think evil has found a technological way to recreate this process, but control the body and mind of a human, in a more complex manner.
Just the first thing that occurred.
After all - 'free' usually means 'bait', and they want to trap and control us, what better way than with food.
Burgers = cheese
Humans = mice
They want us to destroy each other.