Couple of recent ones:
Cycle goons on trains- dressed head to toe in sponsored lycra and insisting on wearing your helmet indoors, obnoxiously taking up half the carriage with your huge bike, then hiking it up the escalator to get out of the station. Please fuck off. If you love cycling so much, cycle the 50 miles from home to work.
Smokinmg vs vaping. Just because I am smoking an e-cigarette does not mean you can rock up right next to me and light a cigarette, it is not the same, and you stink. Please go away.
Also @ the vaper who smugly flouts the unwritten rule about not doing it in enclosed public places, please stop looking so pleased with yourself outside the office Starbucks with your stupidly massive machine every lunchtime.