Queues
When I arrive at a bus stop to get the bus somewhere and there's a queue I walk to the back and wait as queue etiquette dictates. I then file into the bus in the order we queued in because the other people were in the queue before me and thus have first choice of seats.
I don't appreciate it when people see other people queueing for a bus so they wander near to the front of the queue and stand by a wall pretending they're having a fag or admiring the lamp post and then when the bus arrives they jump in front of the entire queue even though there were 30 people there before them.
I've actually lost count of the amount of people I've yelled at about the queue or even just shoved out of my way because they're trying to be a cheeky fucker.