What I have noticed is that sarcasm really gets under a supervisors skin. Remember they have certain numbers and metrics to meet but they have no protection and can be let go at any time. And s#*# always rolls down the hill, meaning that they get chewed out by their superiors. This is why they are always sweaty and angry. For the most part ignore the gung ho attitude but if a supervisor is particularly threatening and angry all the time ive notice that sarcasm really gets under their skin. Always say "i am working safely and to the best of my ability". Dont lash out and talk back to them because thats just another thing they can add to your rap sheet. If they put you in a really stressfull and messed up position with no help, stop the belt and follow the methods. Dont be a "runner gunner" because that is exactly what they want. What i have noticed at ups is that the reward for working your butt off is more hard work and they will ever so slightly increase the work load on you. Slowly, but surely. Remember to follow the methods, stop the belt, maintain egress at all times. Eventually they will tire of this and back off of you. If not, file harrasment grievances. Many a time that a supervisor has backed off from me because of threat of paper work. Also remember you can always ask for a shop steward to be present at all times while being disciplined or talked to. I understand that many locals, including mine, have a weak steward but it still creates scene that most of the time they do not want to deal with. Best of luck my friend.