Not the smartest approach bud.When i've encountered someone like that flipping out on someone in retail i try to belittle them with words & make them feel like an asshole in front of everybody,sometimes they'll apologize or just walk away.Have to admit when i'm in a hurry & they fuk up my order it does piss me off,but yelling at them doesn't solve the problem.Btw watch whose coffee you knock over or "60yr old man" you decide to lay the boots tne of my dad's good friend's is a unassuming 60+ retired marine that taught hand to hand combat for most of his life.If you tryed that with him you'd be on the ground quicker than you could blink in a pool of blood.