Reminds me of a dork we had onboard one day. Some exhaust entered the cabin on engine start with a tailwind. The FAs let us know that somebody was concerned. We made a nice PA explaining the phenomenon, and the fact that it would clear right up. Well, this idiot was sure something was wrong with the plane, and insisted we let him off. We RTG, the fumes are long gone, of course, and after shutdown he decides he wants to stay after all! DENIED!