pugnacious — eager or quick to argue, quarrel, or fight; combative

a red-faced student with clenched fists leans forward aggressively toward another student who is simply trying to eat lunch. The aggressive student points angrily and opens his mouth in a shouting gesture over something trivial like spilled milk. The peaceful student looks surprised and defensive, raising his hands to calm the situation. Other students around the lunch tables stop eating and turn to watch the brewing conflict with concerned expressions. someone being eager to argue and fight over minor issues