What grammatical errors really piss you off?

[paperjam]

[ QUOTE ]
Punctuation misuse really bothers me actually [mostly commas but it extends beyond that].

And that loose-lose thing mentioned earlier.

[/ QUOTE ]

I think I know why you're confused. It's because the other night when we were hanging out, and I told you "Your mom is a big loser," I think what you heard was "Your mom is big and loose."