Old people in banks/shops.
I'm one of those guys that times my day so everything fits nicely into place, or in other words, leaves everything till the last minute. I'll calculate the latest time I need to leave the house before work, maybe allowing a little for traffic/going to buy some fags.
Now going to the bank, you expect a line of people so I give it a little bit longer, but almost every time without fail the bank is full of pensioners, who just stand at the till talking about their life, or their holiday, or what their thrid grandchild is currently doing at uni. They don't seem to care that a line almost out the door is forming behind them and at least some of the people in it have more important things to do that day.
So finally, one leaves, the next one goes up. The cashier asks out of obligation "How are you today?" and it begins. "Oh I'm alright dear, my leg is playing up a bit though, going to go to the doctors this afternoon. I didn't want to go but my daughter Janet said I should."
"Aw, well at least she cares about you"
"Yes she's a good girl, she got married last year, had a big service down the church, ohhh the weather was lovely and I wore blah blah blah blah..."
And you stand there and suppress the need to shout "Hey can we move it along a bit, some of have work to get to!"
It's a really minor thing granted, but its one of the few things that really pisses me off.