Gisele Bundchen Was a Gas With Her Sister in Bikinis on the Beach

What are sisters for? It's an age-old question, one in which there is no right answer. From the front these two are very hot. And, as illustrated below, from behind they're even better. Why? Because from behind they're showing us their ass, and something about an ass and the brain will follow comes to mind, but not enough that I can quote it. 

Via NS4W