On the level Motel. Kill the Goon in the bottom left corner, he’ll drop a Microchip. Interact with the black platform on the bottom right using it. Obtain a soda from an ambulance or kill bikers until they drop one. (It’s guaranteed that one biker drops a soda in the mission, but it’s random. Not to be confused with Goons.) Use the soda on the platform and the aliens will arrive to party it up.