Curling games begin and end with a handshake and greetings of "Good Curling" between each of the competitors.
In most sports the rules are enforced by referees or umpires, who impose penalties and legislate fair play. Breaking a rule often doesn't matter unless the officials see it, and good sportsmanship doesn't seem very important to many of the athletes.  The sport of curling is completely different. Except for certain national events, we don't have referees or umpires. The curling rules are enforced by the competitors themselves, and breaking a rule is a big deal even if no one else sees it.

Click here for an article from 2018 about Curling Sportsmanship