This sign makes it clear that cars are prohibited from exploding in China. Violators will be shots and their parents will be charged for the bullets.
Rachel says: "I saw these strange signs all over Beijing when I was there this past summer. None of the native Chinese people I traveled with knew what they were supposed to mean. Even our taxi driver didn't know. Anyone have a clue?" Link (If you know what the sign really means, post your comment here. Please don't email me about it.)
Update:
(Click on thumbnail for enlargement) In this Cambodian store, you're asked to leave your knife, pistol, grenade, and dog at the door. But machetes, sawed-off shotguns, and C4 aren't expressly prohibited. (Thanks, Waylon!)