If you're driving a big truck, and you come upon a rickety old bridge you have to ask yourself, "do you feel lucky?". How has your day gone so far? Have you won some cash on a scratch off? Did you get digits of a beautiful girl the night before? Do you travel with D&D dice? If so, what number do you have to hit to make this bridge safe? Or you could use that rare "common sense" gene. No? O.K.