- In "Dinner Party", poor Clarence touches fiberglass thinking it was cotton candy and his hand gets all swollen while he yells in pain.
- Clarence nearly falling through the weakened floor of the attic. Luckily, Chad was there to save him... But then Clarence, Chad, and the others fall through the floor anyway, since the floor couldn't support the other kids' weight.
- In "Rise and Shine", when Clarence encountered a very hungry, very angry, mountain lion in his back yard. The way the police man talked about a previous mountain lion attack moments before certainly didn't help.
- In "Puddle Eyes", Clarence running around the playground (and later the school) unsupervised while he's blinded by mud. The fact that he could have accidentally run into the road and gotten hit made the scene hard for people to watch.
- Also Clarence imagining skin growing over his eyes.
- From "Too Gross For Comfort" we have Julien's story where he got bitten by an insect. Said insect laid eggs in his arm and the doctor pulled an insect out of Julien's arm.
- Jeff's freakouts and creepy behavior towards girls can be this for some viewers.
- "Rough Riders Elementary" is full of surreal creepiness. At first, Rough Riders Chicken comes to sponsor Aberdale Elementary. Then they take over the classes and brainwash the children using a special sauce. Soon the whole school is turned into a fast food restaurant with the children as mindless employees. Then it's revealed that Rough Riders Chicken is actually a cult that is converting the kids into followers. Fortunately, it's revealed that this is all just a story Clarence made up for a report.
- Josh's Sanity Slippage in "Nature Clarence", where he began rambling about how he and the kids will have a happy home on Sheep's Bridge. In his underwear, with a very disturbing look on his face. Later in the same episode, a goat tears part of his ear off. Unlike most cartoons, which would have Josh's ear back the next time he appears, Josh's later appearances have him with a bandage over the hole where his ear used to be. Likewise, after having an eye impaled by a fork in "Neighborhood Grill", later episodes show him wearing an eyepatch. In "Chimney" he appears to be manifesting symptoms of schizophrenia as he talks to a dog while riding the rails like a hobo... then falls, to severe injury, from a moving boxcar. Next we see him, in "Chalmers Santiago", he has a hook prosthetic where his right hand used to be.
- In "Straight Illin'", Clarence becomes increasingly sick from being dared to eat 500 devilled eggs, to the point where his appearance starts becoming infected and zombie-like. The episode was so disturbing, Cartoon Network outright banned it.
- In "Hurricane Dillis", Clarence's grandmother visits, and her manic, erratic behavior (including being missing for two days, messing up the house, and thinking her daughter is still with Clarence's biological father) seems to indicate the onset of senile dementia... a very real concern for the adult children of aging parents.
- Oh god, where to start with "Lil Buddy"...
Im glad he was fine in the end, but this really makes me wonder about Clarence. I mean, lets admit it. Missing half of 1 recess is pretty trivial. Sure maybe to a 4th grader recess means a lot more, but Clarence way over reacted to that timeout, to the point it was frightening. This really makes me wonder what Clarence would be like as a teenager. I mean, if something trivial like that brought him to that horrid emotional state, then just imagine if something REALLY traumatic happened in his life. It would be much worse than what we saw here.
- The title card alone is creepy as all hell, with Clarence on a backdrop of the surface of a Creepy Doll.
- The Lil Buddy commercial plays out like those classic 80s commercials for a doll for boys. The boy in the commercial dressed as Lil' Buddy plays with his Lil Buddy doll in the commercial along with another boy who looks very unsettled playing with the boy and his creepy doll.
- Ms. Baker and her students are very creeped out about that commercial, and Clarence's little buddy.
- Let's not forget how far Clarence crosses into the Despair Event Horizon either.
- To quote a Tumblr comment:
- "Goldfish Follies" can become this thanks to the revelation that the old-timey "rubber hose" cartoon style seen in the episode was just Clarence's imagination. Try watching the episode again and imagine everything happening without the old-timey cartoon filter, and you'll realize that there's a really good reason the goldfish isn't moving by the time Clarence gets it home...
- Jeff's obsessiveness and jealousy over being forced to share his birthday party with another boy in "The Big Petey Pizza Problem" culminate in him starting a fistfight at a bowling alley, and then standing over the other boy with a bowling ball in his hands, as if getting ready to smash the kid's skull in with it. Jeff can be very disturbing when he doesn't get his way. Also, Gilben's unnatural posture— arms stiffly akimbo, perpetual rictus grin, open, unblinking eyes— looks like a cross between a mannequin and someone with a bizarre neurological disorder and seems quite unsettling, not to mention that he thrown a punch without even moving!.
- Lots of the parts in "In Dreams", especially when Clarence realizes he's dreaming and everything goes completely crazy. Also, the narrator of the dream show Clarence watches is also seriously unnerving, what with the blank stare and creepy monotone voice...
- At the end of "The Tails of Mardrynia", Mr. Bugsby crawls into Belson's eyelid, and he and Mrs. Bugsby make a home in his eye socket. And while this happens, most of the other kids are laughing at Belson freaking out about it!
- Percy ends up getting a little too obsessed with the fantasy world he created full of talking animals, deciding to lead them all in a "war" against the "Pink One" (Clarence). This results in Percy walking into Clarence's room and dropping all the animals on him while he's sleeping; not super-scary, but definitely not something you'd want to wake up to.
- The end of "Game Show", where the game show host falls into a pool, washing off his makeup- and revealing him to be some sort of vampire-esque creature. He runs off screaming "DON'T LOOK AT ME!"
- The show takes place in the same universe and town of Over the Garden Wall. In one episode, there were a bunch of trees with faces on them, and one of them spoke, meaning that they were Edelwood trees. While this in itself is horrifying, it was Played for Laughs. But this confirms that Edelwood trees aren't just a thing that only happens in the Unknown but they're a naturally occurring phenomena.
Nightmare Fuel / Clarence