Just thought of another one: when the hero realizes how the bad guy will carry on its plan, especially when it's a conspiracy, and when he tries to explain it to whoever is naturally and professionally inclined to stop him, such as policemen or secret services, he says just some catchphrases as "you don't understand" or "please, this is gonna happen now, let me in".
Geez, the truth is on your side, if I were in such a situation, I'd do a fast exposition dump to explain *exactly* what I'm talking about. But no, he/she has to act and sound crazy and of course be stopped because there has to be drama until the last second!