How can you cause a traffic jam inside a multi-story car park? The obvious answer is drive in and stop. But what if you wanted to follow all the rules of the road and social convention in such a way that no one would get upset with you? Well then, you need some like minded people to help, or hinder, depending on how you look at it.
First of all, group up. If you're coming into the car park and looking for a space, join the (on-brand) blue team. If you're leaving, you're on the black team. Find a couple of team mates and stick close to each other; we'll need long chains to make this work.
Secondly, blue team must block the exit and black team must block the spaces. Blue team can do this by occupying the ramp by the exit and the exit itself. At the same time Black team must try and hold the downward ramp and the area in front of it.
If anyone complains to you:
“I'm just trying to get a space/go home” as appropriate.
Holding this formation for a few minutes without intervention might be enough to permanently disable the facility. More people will unknowingly join each team which will not only add to the gridlock but comically result in more spaces being made available on higher levels.