Usage notes: Teh can be used in grammatically different ways than the word "the", in a similar way to the spanish word "el". For example, "He is teh stupid." is an acceptable sentence, whereas "He is the stupid." is not.
I don't think this is true. The regular "the" is used in the same way. Compare these Google searches:
It says deliberate misspelling of the, but I find it I personally often unintentionally misspell it (typo), it should be made note of that it is not always intentional, and, if verifiable, that its etymology is that "the" has been simply misspelled a lot and the apparent change of spelling has influenced a separate usage from "the".
I agree in that it almost definitely originated as a typo. And as with most things on the Internet, was probably mocked so much it became a meme. I'd continue to argue that memes are not words, and shouldn't be treated as such. (We going to add cheezburger now too?)
Considering it is a deliberate misspelling, there is no proper usage