Sitting in the back of a cab
While it's customary for Americans to hop into the back of a cab, in Australia, New Zealand, parts of Ireland, Scotland, and the Netherlands, it's considered rude not to ride shotgun. Whereas cabbies in the US will sigh and reluctantly move their newspapers and lunches from the front seat, in other countries it's a matter of egalitarianism.
[Photo via @evachen212]