[matheusmoreira]

Generalizing the advice..

Don't challenge people. Don't insult people. Don't humiliate people. Don't threaten people. Allow them to maintain their self-respect even when they lose. Don't rub it in. Give them a face-saving exit.

Plenty of violence and aggression is caused by violation of the above rules. They seem simple but they're broken on a daily basis. Famous last words: "you don't have the guts".