Let's get contentious - the types of people you can't stand

People who drive slow in the fast lane. (I'm not against people driving slow, but there's a lane for that. If they're going to drive slow, then they should stay out of the fast lane. Slower traffic keep right.)

People who park in disabled parking spaces when they're clearly not disabled.

People who send you an e-mail at work and then complain if you don't respond to their e-mail within 5 minutes.

People who don't understand the difference between "Reply" and "Reply All" in Microsoft Outlook.