Must have, must've...NOT must of!

Common Core...

It's not important that the grammar is correct.
It only matters that the stupid sheep can sort of interpret your meaning.

Why not just spell it "musta". That way it's easier to type and people know you are smart enough to figure that out.

I dunno - it prolly ain't right but who'm I ta say?

Yeah that's actually less annoying to me.

The entire book reads like it was written by a 12 year old for 8 year old's so it's quite understandable.

Not accepted by educated Americans, but many people say it that way very clearly, intentionally.

If it's not accepted yet, it will be soon.

There is no 'must've', it doesn't exist. Try again.

I went to high school in the USA in the 1960s and a few kids in my senior class were writing "of" in this context back then, so it's an ongoing thing with little-to-no hope of being cured.

I agree. Must have or must've, should have or should've. If they would think before they write it down, putting "of" in there doesn't make any sense whatsoever since of is not a verb.

The must of the rotting oranges was nauseating.