Pretty much the entire episode "Where Lies the Engulfer". Zak and Doyle are at an abandoned town for Zak's "final exam". The two of them obviously need their own spinoff show because of the epic hilarious lines between one another. Granted, a fair portion of it is Nightmare Fuel, but their interactions still qualify.
How about the part of "Kur, Part 1", where Doyle walks into a fancy restaurant in England, sits down at the table of one of Argost's biggest sponsors, grabs the guy's lobster and starts chowing down while asking him about Argost. A little while into the scene, a waiter tries to hit him from behind, and Doyle just whacks the guy in the head with a serving tray without breaking stride. And then proceeds to beat the crap out of everyone in the room with little to no effort.
Doyle and the very out-of-shape Van Rook having a somewhat partnership in Season 2. Pretty much everything they say to each other counts as this.
You know what, let's just save time and say Doyle in general is a walking CMoF all on his own.
You have to get the Genius Bonus for this one to be funny, but Van Rook being outraged over something costing 1200 drams. Twelve hundred Armenian drams is the equivalent of two and a half American dollars; if you were unsure of how cheap the guy was before, this should cement it for you.
In "Once More the Nightmare Factory," with the family safe, Doc proclaims victory "for now." Then a huge cryptid rises out of water behind him.
Zak: Dad? Doc: No. I don't care. I'm not turning around to look at it. It's over. We won.
Van Rook summing up his opinion of Piecemeal in "Target: Fiskerton":
"Everything about you disgusts me."
"Munya, it appears we have lost. Naturally, I blame you. Take us home so you can hide your shame."
Why would Drew throw a tv? Because she gets in the zone.
Zak gets good use out of a normally horrible pun when listening to Wadi's explanation on why the rivers turned to salt:
Wadi: It's not a fairy tale! First I took the Flower out of the river, then the Salt Man—
Zak: Whoa, whoa, hold up... there's a Salt Man now? (laughs) What happened then? He ''assaulted'' you? (Laughs)
In "Kur, Part 2" when Argost offers to help Zak learn to control his Kur powers, Zak is naturally skeptical. Argost responds by saying that of course he plans to manipulate Zak, then betray and kill him when he's no longer useful, and that his only hope would be to somehow learn enough from Argost's lessons to outsmart the smartest being on Earth. Zak prompty agrees, leading to Fiskerton's funniest and most appropriate "Say what!?" of the series.
Doc Monday licking the mirror and saying "Shiny" in "Black Monday".
This classic line from Argost after being defeated:
Argost: Munya, it appears we've lost. Naturally, I blame you. Take us home so we can hide your shame.