Originally Posted by Hils
DS8 and DS10 are starting to develop a sense of humor
Some may say this sounds rather late. Interested parents may wish to use a web search to locate lists of developmental milestones.

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Age appropriate movies for humor development? What would be good movies to watch with them?
Movies may not be an effective media for parents to use in cultivating a child's emerging sense of humor, unless watching at home and stopping the scenes to discuss and explain.

Many children enjoy books of riddles and puns which may help acquaint them with word play such as homonyms, spoonerisms, oxymorons, and more. Word play may form the basis of much good humor. There are also websites which may be of interest to parents as a resource, such as Fun With Words.

A positive, intellectual sense of humor may be based on bonding over a shared understanding of word play... as opposed to a negative or ironic sense of humor based on win/lose scenarios such as mocking or schadenfreude. This article from the Davidson Database discusses humor, including Constructive vs. Destructive humor.

Beyond word play, there are many children's books categorized as "humor". Utilizing the search feature on the barnes&noble website retrieves many selections. This old thread on humorous books may also be of interest.

The word game Apples to Apples (also available in junior editions for children) presents humor and the opportunity for discussion of why something is funny.