Your sister is your BFF, although she's so much more than the textbook definition of best friend. You've been paired together since you were kids and have gone on many great adventures together over the years. You have what feels like a million inside jokes, and whenever the nostalgia hits, she's the first person you text. You may not live under the same roof anymore, but you still talk all the time in your group chat. Whenever you’re finally reunited, one of the first things on the agenda is to get a selfie together.