Brazil isn't just the site of this summer's World Cup and the world's most ridiculously hot-looking humans. It's also the home of Rio's unique beach culture, where people don't just sit stoically in the sun—they mix, play, mingle, and party. Whether you're headed down for the Cup or just want to import some of that sexed-up energy to your local stretch of sand, we'll show you how it's done (and what swim trunks to wear)