I'm not one to sport bumper stickers on my car, but I might have to put one on anyway. To those who don't know what it symbolizes, I copied this from the linked page:
"The bumper sticker is based on the famous flag designed by American Revolution era general and statesman Christopher Gadsden. The yellow flag featured a coiled diamondback rattlesnake ready to strike, with the slogan 'Don't Tread on Me!' underneath it. Benjamin Franklin helped make the rattlesnake a symbol of Americans' reluctance to quarrel but vigilance and resolve in defense of their rights. By 1775 when Gadsden presented his flag to the commander-in-chief of the Navy, the rattlesnake was a symbol of the colonies and of their need to unite in defense of threats to their God-given and inherited rights. The flag and the bumper sticker symbolize American patriotism, the need to defend Americans' rights, and resistance to tyranny's threats to American liberty. Those threats included-and include-illegal taxation, profanation of Americans' rights, and violation of the fundamental principles of American law."
It's also the avatar used by Veritas.