If you're having trouble practising speeches in your dream, try doing a speech for the sake of your own amusement first. Like with what Bechillbro said, you could try inciting a riot or something just for the lulz.

Have fun with it first, then it should be easier to confront seriously because you're somewhat used to doing it in a relaxed manner.

I can't really think of that much off the top of my head, but why not try something stupid like deliberately misguiding students during a sex-ed lecture.