There is a form of humour which is quite unintentionally. It arises when a person realises the ludicrous nature of a tale which is being told.
Often the “tale” is nothing more than a big “whopper”. A child might be “caught out” in some mis-behaviour and he/she will tell such a huge whopper to explain the situation, that the parent or teacher can do no more than to burst into laughter.
The laughter is rooted in “do you expect me to believe that!”
There is a gorgeous example of this “big whopper humour” in the book of the Exodus.
The people are in the wilderness, but their leader Moses has disappeared. He is off on one of his “terribly important consultations with God”.
The people have lost confidence in their “leader in absentia”, so they prevail upon his brother Aaron to fashion them new gods.
Aaron gets them to surrender their gold, out of which he fashions an idol - a golden calf.
When Moses gets back from his “retreat” he is royally ticked off, and demands an explanation from Aaron.
Then comes the “whopper”: Aaron tells Moses that the people gave him their gold, and that he threw it into the fire, and (all innocently?) Aaron says “then out came this calf”.
It’s a fabulous lie, one which is so brazen that we can do nothing more than laugh.
Here is the story from the bible. I have chosen the King James (Authorised) Version because of its lovely older English.
1And when the people saw that Moses delayed to come down out of the mount, the people gathered themselves together unto Aaron, and said unto him, Up, make us gods, which shall go before us; for as for this Moses, the man that brought us up out of the land of Egypt, we wot not what is become of him.
2And Aaron said unto them, Break off the golden earrings, which are in the ears of your wives, of your sons, and of your daughters, and bring them unto me.
3And all the people brake off the golden earrings which were in their ears, and brought them unto Aaron.
4And he received them at their hand, and fashioned it with a graving tool, after he had made it a molten calf: and they said, These be thy gods, O Israel, which brought thee up out of the land of Egypt.
Later in the story
21And Moses said unto Aaron, What did this people unto thee, that thou hast brought so great a sin upon them?
22And Aaron said, Let not the anger of my lord wax hot: thou knowest the people, that they are set on mischief.
23For they said unto me, Make us gods, which shall go before us: for as for this Moses, the man that brought us up out of the land of Egypt, we wot not what is become of him.
24And I said unto them, Whosoever hath any gold, let them break it off. So they gave it me: then I cast it into the fire, and there came out this calf.
See also http://www.2camels.com/big-whopper-liars-contest.php