I think more signs should be like those they put up around the subway yards to keep people from hopping the fence: “Trespassers May Be Electrocuted.” Instead of just telling you what to do, it vividly describes the consequences of not doing it.
     So, in that vein, how about “No Smoking within 50 ft . . . BOOM!”
     Or “Slippery When Wet . . . CRASH!”
     Believe it or not, what’s got me thinking about this is the guy who sells ice-cream in our neighbourhood; and who, apparently, has already adopted this approach with the warning painted on the back of his truck: “Caution Children . . . SLUSH!”