How we exclude an undesirable interlocutor from a conversation. In the following figure, you see that two interlocutors are turned at an angle of 45 ° to each

In the following picture, you can see that the two interlocutors are deployed at an angle of 45 ° to each other, which allows the third person to join in the conversation.
An open triangle allows the third caller to connect to the conversation
If the third interlocutor wants to connect to the conversation between those who are in a closed pose, this can be done only if the first two are in the corners of an imaginary triangle. If the presence of the third is undesirable, the first two simply turn in his direction of the head. At the same time they can smile with clenched lips.
It's time to leave - the interlocutors are not thrilled by the appearance of a new person
A conversation between three interlocutors can begin in the position of an open triangle, but gradually two of them can move into a closed pose, thereby eliminating the third one from the conversation. Having noticed a similar situation, the third one should leave to avoid embarrassing situation.