You know people who can understand each other just with a look? Usually you know that person for a while. But you understand what a wince means in a certain situation or know, without looking at them, that they are unbearably excited. I sometimes get that way with my brothers (although they aren't exactly an excitable bunch; normally they are the ones confused by my excitement. But never mind).
Do you have any characters that are excited or confused? How can they communicate, and who can they communicate to, where the will know the situation immediately without even trying? Who will know, immediately, what that little wince means? Who does your character understand? Try and show that understanding this week.