Shake hands and come out fighting.
I speak around the country to court reporters. They are the people, predominately women, who record every word, said in the courtroom or in a deposition. They have a lot of stories about the lawyers they work with. Many of them talk about a particular handshake ritual they see occur at the beginning and end of a trial or deposition.
Lawyers who have known each other for years will come in and shake hands with each other. Then those same lawyers will spend the entire day or trial saying horrible, derogatory things about one another, shake their fists, frown and nod negatively, and roll their eyes, and express other disrespectful gestures and sounds when the other lawyer is talking. They will in effect go to battle with each other, smile and shake hands again and say, "Let's go out for a drink." They are buddies again.
The court reporters were flabbergasted. How can guys do that? How can you shake hands and be friends again with someone who treated you so abominably? This is actually part of Gamesmanship.
The game rules say, "Shake hands with your opponent, and come out fighting." And when the game is over, the game is really over, so leave your bad feelings on the playing field and shake hands again.
This ritual is repeated by men over and over on the sports playing field as they grow up so that in adulthood it is second nature to them to shake hands and come out fighting.
Read some interesting stuff here.