In other words, we as speakers try to contribute meaningful, productive utterances to further the conversation. It then follows that, as listeners, we assume that our conversational partners are doing the same.

You can think of reasons why someone might be uncooperative in conversation (maybe they’re being interrogated for information they don’t want to give up; maybe they hate the person they’re talking to; maybe they’re just crazy) but in the vast majority of conversations, it’s safe to assume that both participants are trying to be cooperative.

This assumption that the people we’re speaking to are trying to cooperate explains two things:

(1) Why speech errors are often ignored (or even go unnoticed) in conversation. As long as the meaning the speaker is trying to get across is clear, the listener usually gives them the benefit of the doubt and focuses on the meaning.

(2) Why we can find meaning in statements which, on the surface, seems ridiculous, untrue or unrelated (i.e., metaphors, sarcasm, overstatement, understatement, etc.) Rather than assuming that our conversational partner is lying, crazy, or speaking at random, we assume they’re trying to get across some meaning, and we can figure out what that meaning is.

To further specify the cooperative principle, Grice (1975: 47-48) introduced four categories of maxims as follows:

(1) Maxim of Quantity
Make your contribution as informative as required. (Don’t say too much or too little.)
Make the strongest statement you can.

(2) Maxim of Quality
Do not say what you believe to be false.
Do not say that for which you lack adequate evidence.

(3) Maxim of Relation
Be relevant (Stay on topic).

(4) Maxim of Manner
Avoid obscurity of expression.
Avoid ambiguity.
Be brief (avoid unnecessary prolixity).
Be orderly.
Humor is kind of art, and it takes on different forms, such as drama, painting, dancing, music, joke, story, and novel. In terms of its language, humor can be regarded as a kind of writing style, an artistic form, or the effects created by its language. Humorous effects can be achieved through oral or written language, especially by means of certain language devices. The linguistic core of humor consists of certain language components or language phenomena which can cause misunderstandings. Such a linguistic core is produced by the violation of certain maxim in the cooperative principle. 英语幽默的语用研究(2):http://www.youerw.com/yingyu/lunwen_8811.html