One clean joke for children is, "What do you call cheese that doesn't belong to you?" with the answer "nacho cheese." Another classic joke that is appropriate for children is, "Why was the number six so scared of the number seven?" The answer is "seven eight nine."
The joke about the number six fearing the number seven is humorous because the pronunciation of "seven eight nine" is the same as "Seven ate nine." Thus, the implication of the joke is that the number seven is fearful because it ate the number nine.
There are also many knock-knock jokes that are appropriate for kids. For example, after the joke-teller says, "Knock knock," and the child replies, "Who's there?" the person can respond, "Lettuce." Then, after the child says, "Lettuce who?" the person replies, "Lettuce in. It's cold outside!" This joke is another play on words because "lettuce" has the same pronunciation as "let us."
Another knock-knock joke involves saying, "Interrupting parrot," after the child asks, "Who's there?" Then, when the child asks, "Interrupting parrot who?" the joke-teller interrupts the child with a loud squawking sound like the one parrots make.
On Christmas, it is fun to ask a child what the definition of "claustrophobia" is. After the child either says she doesn't know or begins giving the literal definition of the term, the joke-teller replies that claustrophobia is the fear of Santa Claus.