You may have seen/experienced it or you could be the one committed it. Let's see....
Here are mine:
1) Incoming passengers blocking the passage way of outgoing passengers.
2) A middle age lady wrestled her way to a seat as if she owned it, leaving two passengers in front of her fumbled.
3) People just cut in your queve/way/view simply because I didn't inch myself to the door.
4) There will occassionally be one or two rushing out of the cabin to be the first at the escalator.
Hawker centres, coffee shops or Restaurants:
1) After meal, people conveniently threw used tissue paper (either for their mouth or their nose) onto the plate or into the soup.
2) Saw a coffee shop attendent using the table cloth to wipe his hands which he used to blow his nose.
I will add more when I thought of more...........