There are many things on the Internet that can spook you out, and can be used for SCP references. Here are some Ideas that I've made in the top of my head, based on other creepy stuff (I'm new here, so expect these to be crappy):
* A series of books that have a alternate spelling of the series' name. Many people remember this alternate title, and claim that it was changed due to universe swapping, a.k.a The Mandela Effect.(The Berenstein/Berenstain Bears Parallel Universe Theory)
* A poem that would bring bad luck if you fully read it. Some things are redacted to prevent this bad luck from spreading on to people. (Tomino's Hell)
* A still beating heart from an unknown creature. The heart looks abnormal, like it had been fused with maggots and tumors. The creature is still there, but dead. One of it's eyes are still open, and it's said to drive one of the scientist's mind insane. (The Tell-Tale Heart)
* Another book, but this time, it's made by a mentally insane woman. The book contains visuals of the insane woman's dream, and the stories of the dreams. There is also a game made by the woman that has visuals of the book in it. It's contained due to after-effects of the game cause nausea and headaches due to the visuals of the game. (Lovely Sweet Dream and LSD Dream Emulator)
* A group of puppets held by a multi-armed animatronic creature. It seems to have an obsession of education, and wants to educate things, even if they're non-living or imaginary. (Don't Hug Me, I'm Scared)
* An old version of a well-known movie that contains disturbing visuals and nightmarish alterations. Some may be minor, but some are story-changing. There are also papers stating the hard work making the old version. (The Black Friday Incident)