“ Have the PCs rping Orcs or Goblins or some other race that normally exists only as things to cut up with swords.”
“ A people who believe it is incredibly impolite to speak to anybody they meet for the first time. They believe their actions should speak for them until they are comfortable in each others presence and can then trust each other. Only then would converstation be appropriate.”
“ What if a invisible person could see other invisible creatures? All you would need to do to check for nasties hiding around is turn invisible.”