Slang for propaganda that tastes good on the surface, but eventually kills you. A certain Jim Jones took his cult of almost 900 people to Africa and when investigated for human rights abuses, gave the entire cult Kool-Aid laced with Cyanide to kill them and cover his tracks, telling them that the Russians were coming to kill them.
Thus, the association of Kool-Aid with political propaganda and lies.
Dumb Democrat: Dude, this new guy Obama is so great. He is going to lower taxes, help out the middle class and stop corporate fraud.
Smart Republican: (under his breath) Drink the Kool-Aid, my children...