Being vulnerable before someone is hard and honest.
When you are in a meeting, it is a key day for you, and you are scared. But bravely you acknowledge that you are scared. For a slight moment you open up your feelings, and then you continue delivering the presentation. That slight moment of opening up is important.
When you are in the final moments of a hackathon, there is some bug, and you are freaked out. You acknowledge this feeling with your partners - "Man, I am psyched due to this bug!". And then you continue your work. This slight connection is important.
There are definitely whys for all these whats. The most powerful one is the skill of being fearless. You overcome your fears before one person, one group, and slowly you will learn to do it at scale.