I feel like most of the hostility that cyclists recieve from automobile drivers is due to ignorance. (and I'm speaking from experience here...not that I ever acted on my frustrations). I'm wondering if anyone has taken the time, and had any success with printing messages to vehicles on T-shirts or bumperstickers, that make them ponder the situation while they're waiting for an opportunity to pass. I was thinking of something "non-confrontational" like...

"Legal Road Vehicle"
"Pass when clear"
"How much room would you want me to give you if we traded vehicles?"
(any longer than that one and I'd need to hand out leaflets )

All you with tens of thousands of miles on the road have certainly thought up better ones than these, what are they? Has anyone given it a try and had some success?