That's how we judge you and how we remember you.
You are presumed to be showing us your real self when you are on deadline, have a headache, are facing a customer service meltdown, haven't had a good night's sleep, are facing an ethical dilemma, are momentarily in power, are caught doing something when you thought no one else was looking, are irritable, have the opportunity to extract revenge, are losing a competition or are truly overwhelmed.
What a great opportunity to tell the story you'd like us to hear about you.