Traffic Jam & pink buses in Tehran
well, here the first thing you'll get confronted to once you'll be there : the craziness of the traffic - so crowded and its "rules".
Basically (and especially in Tehran) one can do whatever he wants to get where he wants, keeping in mind to respect his compatriots (that is to say not bumping them :-D).
See, they have pink buses. Anahita would dream to picture the same ones in Mexico ;-)