I hate when people say "alot" instead of "a lot"  (okay, maybe not so much because it aint intentional)
I hate when people say "to" instead of "too"
I hate when people say "then" instead of "than" - "I'm better then you"

"could of" (and "would of") instead of "could have" is already mentioned in the thread.

What about when people say "I would of done something" when it's meant to be "I would've done something"

...and all this time I just thought I was the one saying it wrong....

I love saying it.

I could care less.

I couldn't care less.

Yes that always annoyed me especially when they are trying to act like they don't care at all.

lolol dis thred sux i cud care lesse it cud of ben bedder

I couldn't care more.

*head asplodes*

Correct expression would be: "I could not care less".
I would simply say: "I do not care"

Would you rather be a person that couldn't or a person that could? I'm one of those people that COULD care less. It's my super power.