They can see the subtle humor in stories and songs that often escapes younger children. They can understand and even tell jokes. By this age humor is more of a shared experience. The creative mind of a kindergartner is fertile ground for jocularity. In fact, at some point during the year you might find yourself thinking that everything is funny to children this age.
Kindergartners can use the simplest prop and turn it into a hilarious skit.
The wonderful comic Jonathan Winters comes to mind. The onset of higher-order thinking skills affects children's humor as they learn how to manipulate words, concepts, and even reality in complex ways. Not Be to Another Kindergartners may find very different things funny. Some are linguistically mature enough to understand puns and other plays on words and even create their own nonsense rhymes. Active and kinesthetic children might find playful falls and silly walks funny but get insulted by nonsense name rhymes.