In Québec, when somebody reacts like Team Leader B did, somebody will invariably say (with rolling eyes):

"Bang, bang. T'est mort sinon j'joue pu" (slang meaning Bang, bang. You're dead or I'm not playing anymore.)

It means the person is immature and everybody knows it - like those little kids playing "cowboys" or "war" and one of the kids is really immature and refuses to play unless everybody follows his rules.