I spit on cars occasionally. People here in Califukya can't grasp the concept of "pedestrians have the right of way" even in crosswalks. When it's just typical obliviousness I let it go but when the driver looks at me and gloats I like to smile, lay a big green one on their passenger side window and watch them stop in the middle of traffic, trying to figure out what to do next.
I have many of times. the person either disrespected me or another person i know or I accidently miscalculate haw far away they were when i spit. ( the last one is the one that happens alot)