Fans of normative signs will likely enjoy this:
25 Signs Made Funnier By People (With thanks to NW.)
I can pretty readily imagine the pattern of events that must have led to it being necessary to post such a sign. After all, if a 12 year old is pumping gas, he may not be mature enough to remember not to smoke while doing so.
I like the verb mood being employed. Is that the optative mood? I’m not sure, but the sentence structure is surely one seldom seen in everyday conversation but pretty common in legal documents. Adding to the legalistic tone is the fact that they’ve decided to go with “dispense gasoline” rather than the more colloquial (and clear) “pump gas.”