Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Nightmare Fuel: The Fairly OddParents
A colorful, cute cartoon like this can't possibly have moments like this, right?
The ending of "Beddy Bye" has what is probably the absolutely worst Gross-Up Close-Up in the history of Western Animation EVER. It's so detailed and really jarring for a show with a simplistic animation style. It tops Squidward'sfamous "sure" glare, which is saying a lot.
There's an episode where Crocker and Norm team up to thwart Timmy by killing him in increasingly ridiculous ways, similar to how the Wile E. Coyote stuff works. Not only is this horrible on its own, but Norm keeps suggesting that Crocker wish Timmy to Mars; when Crocker refuses, Norm takes his lamp and gives it to Timmy, on the condition that his first wish is to send Crocker to Mars, just to show him that it would have worked.
The episode "Timmy's 2-D House of Horror". Timmy deliberately wished for 3-D glasses that would show horrific images so that Vicky and her family would move out of the Turner's home. These images included severed arms in the food and spaghetti and eyeballs. As the purpose of this episode was to show the most frightening images to Vicky's family, the producers HAD to know it was frightening for children and adults.
Timmy's mom: "Who wants spaghetti and meatballsEYEBALLS?
How Vicky sees it as mundane is also terrifying in and of itself. It's already been established she's an Alpha Bitch, but what does this say about her true nature?
In another episode, because of Timmy travelling to the past to prevent his dad from winning a race and thus Timmy's mom, this results in a dystopian future in which Dad becomes a creepy Stepford Smiler to cope with his loss and forces everyone else to be one as well, whom he calls his "children".
The sequence where Crocker had his memory erased as a child. Brr.
"The number you have reached is trying to kill you."
In the episode "Lights Out", Timmy wishes everything to be dark for 12 hours after Poof's crying keeps him up all night. This causes Cosmo and Wanda to become 'Scary Fairies'. Not only do they look scary,◊ they're out to get Timmy, and do various things to kill him. And that picture isn't even their scariest form.
Another very disturbing thing is at the beginning of the episode "When L.O.S.E.R.S Attack", when ''Timmy is incinerated by a type of ray gun. Timmy was standing there and screamed NOOOOO! and then there was a big hole and his hat fell to the ground. Granted, it turned out that it was not really Timmy but it was still unnerving seeing a ten year old boy seemingly vaporized.
Some of Wanda and Cosmo's evil ex-godchildren, specifically Maryanne. What did she do? Wish for the murder of Archduke Franz Ferdinand and his wife. That's right, that little blonde girl caused World War I... and technically World War II. This implies she's the reason there's a "no killing" rule in Da Rules.
Either that or she's just that good at working around Da Rules indirectly. After all, the guy who assassinated Ferdinand was lucky enough to be eating lunch at the right place at the right time when the vehicle came by...
Give us the boy◊. What, can Timmy's parents not find one freakin' normal babysitter!?
The Gigglepies. sure they seem like cute innocent creatures until you discover their Pure Is Not Good. nature and their plans of turning yugopotamia into a nightmarish utopia of happiness and merchandising.
Especially the ending! It's mentioned that every time the Gigglepies land on a planet, they start conquering it with their hypnosis. Timmy had successfully vanquished the threat on Yugopotamia, but at the end, they land on our planet, and this time, WE LIKE THEIR CUTENESS!!