To have a stiff upper lip is an expression used to describe someone who doesn’t show that they are upset or angry.
Ironically, British people are often described as people who have a stiff upper lip and yet, most of my friends flip out when they are angry and upset – there is definitely no stiff upper lip in their behaviour management.
What about me? Well, it really depends on the situation and the person. If it’s my mother, I usually turn bright red and yell my lungs off. However, if it’s a friend, I try to walk away because I think if you haven’t got anything nice to say, then it’s better not to say anything at all. Life is too short for regrets and most people regret the things they say in anger.