Have you ever noticed something like “c’est du deuxième degrè !” when the French talk about jokes? First time I thought I misheard it, but it’s actually true and they actually mean it. Essentially, there are three degrees of humor. The first, based on taking things literally, the second, based on taking things not literally (i.e. irony or sarcasm) and the third, which is based on absurdity and nonsense to a point that the listener is sometimes confused if the other means it or not.

First degree (du premier degré)

C’est deux œufs qui cuisent ensemble dans une poêle bien chaude. L’un se tourne vers l’autre et dit : « Waouh, qu’est-ce qu’il fait chaud ici ! » L’autre s’écrie en panique : « Ahhh ! Au secours ! Un œuf qui parle ! »
When it’s du premier degré, the humor is about the literal meaning. Usually, the joke is based on taking things literally, instead of figuratively. There’s also du premier degré naive, when a person is taking literally what they shouldn’t. An example would be the scene from a French classic Le diner de cons, you can watch it here.
Look at the jokes below to get a better idea.