What are your grammatical pet peeves?

I was recently commented upon (anonymously) in which it was pointed out I use parenthetical phrases too much. Which is funny since I have pointed it out myself multiple times.

It got me thinking about my own grammatical pet peeves. I would never point out these peeves to a writer, but I do have my own and I'm assuming you have your own too. I know we've discussed these here before, but let's go over them again.

~ The misuse of "loose" vs "lose". It happens so often!

~ "Angel" vs "angle". Its such a huge difference!

~ Spelling errors. I'm not talking about the random typo here and there, but when someone really can't spell a majority of words, use spell check!

~ Using the word "that" superfluously. If the sentence can still be read without the word, it doesn't need to be there. I think this is my biggest pet peeve. The word "that" sticks out when I read like a neon sign.

~ Using nonexistent words "irregardless" and "supposably". The latter makes me cringe!

"That" is my list of everything I can think of off the top of my head. What are your pet peeves?