What's your worst pet peeve?

I have many! People who use cell phones while driving, people who borrow stuff and don't give them back, people who mistreat animals (or people, especially children), slow drivers, bugs, constant heat, too much rain, commercials (especially when they're loud), people who stare, people who don't wash their hands when they need to, people who always focus on their phones, video games or computers while you're trying to talk or hang out with them, people who don't clean their homes or after themselves, people who have children when they don't need them, etc :P