Almost everything that goes in Rantanplan's head turns out as this.
Some plots actually qualify as Crowning Moments of Funny. For example, one book involved a Clan war between two families, who recognize each other through their facial features and systematically shoot at each other whenever they meet each other. The problem is, they both aim incredibly bad, so they constantly fail at killing each others and only end up causing collateral damages.
In one book, Joe decides that he and his brothers will cover their tracks by using fake names, calling themselves the Joes Brother: Frank, Louis, Robert and Jim Jones. Needless to say, the others (especially Averell) have a hard time understanding this, and Hilarity Ensues:
Cue William and Jack complaining due to Joe not allowing them to steal anything and begging him to do so just to get decent food:
Joe: No, you idiots!
Averell: But I didn't say anything!
Then when William and Jack try to explain:
Averell: No! I am Idiot! Joe said so!
Joe: I TOLD YOU NOT TO CALL ME JOE! (beat him up) You idiot!
Averell (to William and Jack): See? Told you!
In one scene, the Dalton have captured Lucky Luke, but need to find Rantanplan. They decide to temporarily use Luke's help and advice:
Luke: We need to split up to cover more ground. Joe, go North; Jack, go South; William, go West; Averell, go West.
Joe: What about you?
Luke: Me? Well, I am following you!
Joe: Of course. Don't expect us to be stupid enough to leave you alone here!
(all Daltons follow the instructions and leave, each one believing Luke is following one of the others)
Luke (alone): They really are dumber than I thought.
Marcel Dalton trying to have his nephews working in a bank. Cue this bit of dialogue:
Joe Dalton: Your money! Now!
Customer: But I am coming to give it to you, I want to open a credit here!
William Dalton: Normally, I should be on the other side, with a weapon!
Averell Dalton: Don't you have something to eat?
One book has a Freud-esque psychologist trying to find criminals as test subjects to prove he can "cure" criminals by dealing with their Freudian issues. Lucky Luke and him go to visit the Jail, where the Warden presents him some of the prisoners. Said prisoners include:
A man who refused to pay his food, arguing it was lacking salt, and killed everybody in the restaurant. Sentenced to five years for swearing and rude behaviour;
A man who killed the Governor's stepbrother. Was originally sentenced to death, but the Governor reduced it to three years in jail;
A man who destroyed an entire town, killing twelve thousand people. Sentenced to one year for bothering the neighbours with the noises;
A man who stole a horse; sentenced to prison for life;
Even better is the psychologist's reaction:
Lucky Luke: Does any of those interest you, professor?
Psychologist: Not really, but I'd love to have a word with their judges.
One book has Lucky Luke escorting a team as they go through a town full of Gambling Addicts. As they enter the saloon:
A few panels later, Lucky Luke shoots in the air in an attempt to get people's attention. Someone bet his boots that his gun is empty; Luke immediately shoots a few more times. Cue the guy giving his boots to another guy in the next panel.