Lionel Messi drinks mate. Now David Beckham does, too — and he’s posting all about it on social media. What’s this all about, you ask? We’re here to help. Mate is an all-natural, caffeine-rich South American tea that is popular in countries like Argentina, Uruguay and Brazil. It requires a special cup or gourd and a metal straw and thermos, but very little in the way of preparation, and has ...