Mate.
On the first picture, I’m trying to cosplay Uruguayan people: many of them bring a thermos and a special cup with a metal “straw” and tee-like substance. This substance is called yerba mate and it is ground dried leaves of the plant called the same way. It’s caffeine-rich and unlike tea, you have to fill almost all calabash gourd to prepare mate. Add hot water afterward and the drink can be consumed through a straw called bombilla. And of course, you have to bring a thermal flask with hot water to refill the gourd regularly.
This drink is very popular in Argentina, Paraguay and the south of Brazil, but it’s crazy popular in Uruguay. Uruguayans take it everywhere with them, they walk the streets with flask in one hand and drink in another, and consume 10kg of yerba per person yearly.
Drinking mate is a special ritual: you can only share the drink with your friends, only one person has to be responsible for refilling the drink and ensuring that everyone is caffeinated, and you only say ‘thank you’ in the end, when you don’t want the drink anymore.
You can optionally add sugar, or prepare it with a cold juice or lemonade (it’s then called tereré). But Uruguayans consider all these options as a crime.