Basically when something Fanon like a theory, character, idea, etc gets introduced to a fandom that people think that the Fannon character, theory, idea, etc is canon. Hence the name CANON FANON EFFECT. A "canon" theory, character, etc.

There are two variations to look at this effect. Oblivious or Disregard

Disregard: When people are aware that this character, theory, idea, etc isn't canon. But treat said character, show, theory, idea, etc as if it was canon.

Example: The Creepypasta Fandom often draws Slender man with the operator symbol in the background or most times anything really related to Slender man and sometimes even referrers to it as the operator. Even though the fandom knows that the operator and Slender man aren't the same entity.

Oblivious: When someone isn't aware that said idea, theory, character, etc isn't canon.

Example: The Creepypasta fandom thinks that Eyeless Jack has an origin in which he was used in a sacrifice to become a monster. Even though he never had an origin, to begin with.
Guy1: Hey man your drawing sans eye wrong. It supposed to be glowing with a flame.

Female1: Actually sans never had shown to have a glowing or flaming eye, just one that switches colors really fast.

Guy1: Wait, really? then why does the fandom draw it whenever he's mad or using gaster blasters?!

Female1: Must be the Canon Fanon Effect.
by Mcfat10 March 29, 2020
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