You can disable a self-driving car by putting a traffic cone on its hood:

The group got the idea for the conings by chance. The person claims a few of them walking together one night saw a cone on the hood of an AV, which appeared disabled. They weren’t sure at the time which came first; perhaps someone had placed the cone on the AV’s hood to signify it was disabled rather than the other way around. But, it gave them an idea, and when they tested it, they found that a cone on a hood renders the vehicles little more than a multi-ton hunk of useless metal. The group suspects the cone partially blocks the LIDAR detectors on the roof of the car, in much the same way that a human driver wouldn’t be able to safely drive with a cone on the hood. But there is no human inside to get out and simply remove the cone, so the car is stuck…