In any culture, there are numerous transactions that take place. Some of these are so common as to be invisible and considered self evident by the participants in that culture. In my travels I run into these all the time. Whether it be the proper hand to use when eating, negotiating a taxi fare, or proper greeting styles, it never ceases to amaze me what variety there is. And almost without exception people in each of these cultures assume that their way of doing things is the “natural” way.
This morning’s small transaction was at my local fruit juice stand. Mexico City (and Mexico, for that matter) has an amazing collection of stands that sell fresh squeezed fruit juice and milk and fruit juice combos (called licuados). I purchased a mamey licuado and realized (after my friend Julio told me) that they always make more than will fit in your cup and you are supposed to drink part of it there, then wait for them to top off your cup with the rest. The only parallel I can think of in American culture is the old milkshake can that they would give you sometimes at the malt shop when I was a kid. But I really haven’t seen that in years, and even then they would leave both on the table for you. I think Americans prefer their transactions to be brief, complete and unambiguous. The tiny layer of social interaction that the top off forces is interesting.