Your joke is not as far fetched as one might think! There have been multiple instances [0][1] of a Tesla (and also other car makes, for that matter) where the image recognition system could be tricked.

I wonder at which point we'll deem fooling a autonomous car a misdemeanor instead of changing the underlying AI system.

[0] https://www.technologyreview.com/2020/02/19/868188/hackers-c...

[1] https://www.technologyreview.com/2019/04/01/65915/hackers-tr...