Want real fun? Discuss moon phases, like why there are moon phases and what causes them.
One fun thing to do if conditions are right (standing in sunlight with a crescent moon in the sky), hold up an orange next to the moon, it will be exactly the same phase!
I ran across an author who wrote dramatically that “the full Moon rose at midnight...” and could not understand that that can’t happen.
For more fun, August 21 2017 there will be a total solar eclipse in the USA. If you get a really ignorant person, you may be able to convince them that if they sign their car title over to you, you’ll bring back the sun (you gotta get this done quickly, though).