I'm going to get angry at an elderly man who knocked into me
What happened? Did you get hurt when he knocked into you?
No I didn't get hurt, I just want to go off on him.
I understand that it may be annoying that he knocked into you. But you should try to understand that it may have been an accident and if you're not hurt you shouldn't make it that big of a deal.
I know what I'm doing.
I'm really sorry that you won't accept my suggestion but know that I am only doing this so that you won't do something that you may regret doing. That old man may have a family and may be very upset all throughout the day because of that incident and for the things that you will tell him, so I suggest you just strive to be kind.