I hate the words 'shut up'
I... really really dislike when I'm seriously told to shut up. I'm fine with it if someone uses 'shut up' in a comedic way, but when someone is actually pissed and they say it, it makes me very angry. It's so dismissive and patronizing, and makes people feel about the size of a thumb tack.
So, I promise right now, for the rest of my life to never ever tell someone to 'shut up' when I'm angry.