"SO-BRO" is a term used to refer to a friend who attends a party or social event with you but remains sober. This friend can serve as a reliable guide or protector if needed, ensuring that everyone involved gets home safely. Their presence at the event can provide a sense of security and assurance for those who want to have fun while also maintaining their self-control and safety.
Someone : "Let's drink alcohol."
Já: "Me and my so-bro aren't drinking today."