Never square off if you want to have a casual conversation.
It is about the position of the feet: If the two pairs of feet are pointing directly at each other, that creates an immediate intensity and intimacy.
It focuses and encloses the conversation.
By angling your feet to the left or the right of another, it creates an open stance. One that welcomes others to join in.
It also creates a focal point that is not the two of you: A focus on the third space. The other things worth talking about.
An open conversation, that can go anywhere it wants to.