Public transport when combined with a cultural inability to wait and be polite.
Folk wishing to get on a train are unlikely to be able to do so in comfort until everyone getting off the train has done so because said people are standing waiting to get off in the exact same area that people getting on need to transit through before getting to a seat.
So why do folk, here in Switzerland at least, lose all semblance of manners and common sense when getting on a train? Stand the **** back and let everyone off first (my favourite is some dolt with a huge backpack standing slap bang front + centre on the platform as the double doors open - awareness of one's surroundings isn't a strong point over here either).
Another one is men, of any nationality who drape a oh-so-trendy merino wool cardigan over there shoulders and tie the arms over their chest. A speciality when the weather is far too hot to possibly require the garment, and they look absurd.
Pub behaviour is another one touched upon, but a few on my own.
- Folk who walk in 3 minutes before the start of a major and well advertised televised sporting event and look perplexed/fuming that the place is rammed. Although, that's not really a peeve, just a source of amusement.
- When you're in a larger group and some selfish prats who are in a group of 2 or 3, but sit at a table big enough for 6+ when there's a perfectly good, smaller table right next to them.
- Finally, and I don't know if this really happens in the UK, but people who clearly think they are a "Sartres/Proust in waiting" sitting in a pub for hours nursing an espresso and small glass of water.