a very common drink form argentina,uruguay,praguay and maybe brazil it's like a tea made from mate, people drink it with honey or sugar, and comes flavored. it is ussually grown in the north of the country: misiones, entre rios...
person 1: what's that?
person 2: it;s matecocido, 0ld indigen/indian drink
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.