A few years ago my friend was crying over a girl and I didn't know how to handle it so I just banged him in his chest and he stopped lol
The nod has been bringing the mandem together for years now!
You can crack jokes and be like "I see you and them girls" you ain't even seen him with anyone but that nod has unlocked that
If he nods and you nod back. That's a way of showing that "you're cool you know"