Commonly used by Roadmen in Britain, big man is a term used to tell someone that they are acting bigger than they actually are.
Sometimes you may hear people saying “big man
ting” in that sense it wouldn’t be used to imply someone isn’t actually a big man but instead is implying that the person saying “it’s a big man
ting” is actually a big man”
Big man means someone who is most likely the leader of the
gang.