Once again, I bring you jokes clean enough for kindergartners.
Q: What's the difference between unlawful and illegal?
A: The first means "against the law" and the other is a sick bird.
Q: What happens to a turtle when it dies?
A: It gets rigor tortoise.
(I got that one from an episode of Dharma & Greg. Love that show!)
This one may not be entirely suitable for a five year old, simply because they probably won't get it. Unless they go to Catholic school...
Near the end of his life, Friar Gregory engaged in more and more scholarly doctrinal study. On a trip to Rome, he spent several days in the Vatican libraries studying great matters of Catholic doctrine.
One day from the depths of the library a great cry arose from the stacks. To the astonishment of everyone around him, Fr. Gregory burst out of the library and into the piazza, moaning. Collapsing on the steps with his head in his hands he said, "It says celebrate!"