This is where truly gullible
people are often referred when they self-deprecatingly refer to themselves as the sorts who believe the word gullible is not defined in the dictionary.
G: Yes, I am the guy who believes gullible is not in the dictionary.
M: But what about "gullible" spelled with 4 Ls? I.e., "gulllible." It's because of people like you that silly stuff like that actually gets added to the dictionary.