Old friends talk in three-word references nobody else gets. That’s years packed into a sentence.

Long friendship builds a private language, and it is efficient in a way no new relationship can be. Three words carry a night, a person, a running joke and the reason it was funny, and nothing has to be explained because you were both there. That compression is the actual difference between knowing somebody and having history with them.

It only exists if someone keeps the connection alive, which usually means one person doing the texting. Be that person occasionally with a friend who has drifted. And when you are new in a group, asking what a reference means is a faster way in than pretending to follow.