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Nightmare Fuel: Duckman
There are rapid sequences of images that appear throughout "Love! Anger! Kvetching!" that are Nightmare Fuel. The two most notable are the freeze frame shots of Uncle Mo as a fanged devil and a grotesque caricature of Duckman screaming.
"The Gripes of Wrath": Act three, where the world became a crime-ridden, red skied hellhole. Granted, this section had some funny jokes, but still, what a frightening place.
On the other end of the spectrum, it's a touch creepy how relentlessly happy and supportive Bernice is when the world becomes a utopia.
Duckman eats Fluffy and Uranus in one episode. As if the Squicky mental image of what happens next wasn't enough, they're utterly horrified and disheveled when they're seen again.
"Sperms of Endearment" concludes with Bernice deciding that the world is better off without more Duckmen after a mishap where she though she was pregnant with Duckman's child when she patronized a sperm donor service he's donated to. The episode seems to confirm this, as it ends on a shot of the con artist Terry being burned at the stake by a group of psychotic children resembling Duckman.
"Color of Naught", the third act when Beautex (which was thought to be a beautifying cream) reduces everything it touches to sketch outlines. There's one scene when Duckman is frantically climbing a tower which is quickly being erased from the ground floor up.
Fluffy and Uranus manage to be this in "Short, Plush, and Deadly", despite maintaining their pastel colors and bows. They become enraged monsters that pursue Duckman and an incapacitated Cornfed, not helped when Duckman insults them to the point of hulking out.
In "Noir Gang", Cornfed has a dream about getting it on with Tamara that is cut short when he sees a bomb-strapped Duckman outside. What makes it worse is that he calmly smiles and states that Cornfed is his best friend before he detonates.
This is more in line with Fridge Horror, but there's that Agnes was hiding as Grandma-Ma without anyone knowing. On one occasion, she even flashes a Slasher Smile to the audience.
Tami from "The Tami Show" is an attractive woman who drugs Beverley so she can take over Duckman's family, Yandere style. She viciously kills a neighbor's gardener who witnessed her drugging with a trowel, and survives ungodly amounts of damage from electrocution to being maimed by a ceiling fan, all while sporting an unholy Nightmare Face. She even emerges from the bathtub in a murderous rage and tries to drown Duckman down the drain, only to be devoured by a shark. But the episode ends with her hand rising from the bathtub. And to be make things worse, she appears in a cameo in the final episode at the three weddings. Negative Continuity withstanding.