[kayaker]

Simple solution: golf balls. When some one ahead of me drops a cigarette out the window, I quickly pass and return the favor with a golf ball. I get so ticked when I'm in my 'vette or on my bike. It is just rude.
Having said that, I have been guilty in the past of dumping butts out the window, but I always waited until there were no other vehicles around me.

 

[kayaker]

OK, something tells me if start lofting golf balls at the driver, you have a bit of a law suit on your hands..

yup, which is why you don't loft them directly at the vehicle. instead, you just drop it on the pavement and let gravity and the bouncing energy of the ball do the rest.