When Roma asks Williamson “Whoever told you you could work with men?” he sums up Mamet’s, or at least the characters he creates, idea of masculinity. A man is not a man simply because he was born that way, being a man is earned and in turn earns you respect. The men in this play often insult each other’s man hood when trying to establish dominance. This is a world where being a man comes before all else and if you are on the outside looking in you have to do everything you can to earn that status in the group back.
Manhood in this play is deeply rooted in a man’s job and his ability to do that job. We see this when Levene fills Williamson, a college boy, in on the street knowledge that “A man’s his job and you’re fucked at yours.”. This lets us into the psyche of this group dynamic that a man’s performance in the job is what makes him more, or less, a man. Therefore Moss lashes out at Roma when he feels emasculated by Roma, and the cop. They all know this is the stick for measuring manhood and within that dynamic you can see they react accordingly. This is also why we get lines like Roma telling Aaronow “You’re a, hey, you had a bad month. You’re a good man, George.” This idea of a Aaronow being a good man comes from him proving himself before and therefor they know he is a “good” man because he is a good salesman. The same thing happens when Levene finally makes a sale and become confident and boisterous again because his manhood and identity as a man is tied to his performance and when he does well he has restored himself in that identity.