Perguntas sobre exemplo de orações com, e a definição e o uso de "Marking"

A: It basically means that if you're with a group of people, you're a part of that group and everyone knows it. The sentence is saying it as if being in a large group means strangers won't help, which is a little strange. The phrase on its own can be as simple as some group accepting you, "marking" you down as their own.