If you have to explain it then it is not that good.
Of course, there's, but here goes mine: ...and that, my liege, is how we know the Earth to be banana shaped. This new learning amazes me, Sir Bedevere. Explain again how sheep's bladders may be employed to prevent earthquakes.
Just two. One to explain to the public that everything possible is being done to solve the problem, and the other to screw the lightbulb into the water faucet.
Once when you tell it once when you tell her the punchline and once when she gets it.
It can be a very Hubble-ing experience. These jokes may not be funny for you, but they are Fermi.
