Great teams have inside jokes. Somebody created that belonging on purpose.

Belonging looks accidental from inside it, like the group just happened to be close. It almost never is. Somebody kept showing up, kept repeating the small ridiculous thing until it became a reference, kept pulling newer people into it. Culture is a set of tiny deliberate acts that later gets described as chemistry.

Be that person this week in one small way. Name something the group does, bring the same snack twice, start a running joke that includes whoever is still on the edge of it. Nobody will thank you, and in a year it will look like the group was always like that.