Eh, I'm a very laid-back guy. Little things (and big things) very rarely get to me.
When they do though, I guess the worst offenders would have to be people who cause difficulties in the subway.
For instance, some people just love to start pushing into the train at the platform, before those waiting to get off the train can exit. This slows things down for EVERYONE.
And this morning, a lady (a plumper, to be precise

) was walking up the stairs right in front of me, and as soon as she reached the top, she just stopped, completely blocking the way. This was especially pleasant since my train was arriving. I know your arteries are clogged by Saturated McFat, but would you mind catching your breath just ONE more step away? Please?
Ahem.