1. Used alone to mean that you and your addressee have done something exactly alike (like order something in a restaurant) or think alike in some way. English = 'Hey, we're the same!', 'Great minds think alike!', and so on.
2. Used alone to mean that you and your addressee are, or are to be considered, very close and friendly; or should help each other (say in a game). English = 'Let's stick together!', 'Let's be buddies!', 'We're in this together!' and so on.