please do not spit on the subway

It sounds crazy but it happened today on the 6 train - a guy & a girl got into some kind of dispute, which I noticed when it escalated to yelling. We were at a stop during the whole argument when the guy, already outside the doors, made fun of her do-rag or something. So she stuck her face through the doors & spit at him. He tried to charge back in & continue the argument but it seemed like people blocked him. She cackled, "Haha you wish!" & spit at him again. Fortunately the doors closed & we got moving again before anything else happened. People are crazy.