People that try and turn left out of a gas station into a busy intersection when you’re stuck behind them wanting to go right.
People who clog up the aisles with their cart at the grocery store.
When you’re standing in a long line to order some food and the person in front of you doesn’t know what they want when it’s their turn. It’s like what the hell have you been thinking about for the last 5-10 minutes?
There's other things that get on my nerves but mostly it's just situations that inconvenience others that people let happen because of poor planning and lack of awareness.