If you are of the opinion that the Hebrew Bible/Old Testament is only a serious book about a serious God, then you need to read Simon Holloway‘s post, “The Hilarious Hebrew Bible” over at Divrei ben Abuya. The post looks at a collection of essays that came out quite a while ago: On Humour and the Comic in the Hebrew Bible, edited by (Sheffield: Almond Press, 1990). Simon also adds an example of humour from the Bible of his own.
Joel Kaminsky from Smith College has an article along the same lines which is very good: “Humor and the Theology of Hope in Genesis: Isaac as a Humorous Figure,” Interpretation 54.4 (October 2000): 363-375.