Namely, a small
injustice. You see, if someone offends you in an obviously horrible way, you can
bitch about it without fear of the offender coming back and calling it
trivial. People will agree with you, and hopefully help you fight the
great injustice that has been done to you. You have an
undeniably good reason to
fight back.
However, if someone offends you in a minor but also incredibly frustrating way, it sparks a vicious cycle that becomes more and more infuriating. You bitch about it, but no one really cares because it is minor and has nothing to do with them. If you confront the offender, you will be told that you are taking a fit over nothing, and that you should calm the fuck down. You will make a scene, causing others to tell you to calm the fuck down. You become the offender. No one seems to care about the original minor injustice that has been done to you, and you end up biting your nails and punching walls with a crazed look on your face.
I think this phrase was a quote from someone who died a long time ago, in which case I would like to apologize to a really cool dead guy for stealing his words.