It depends on the situation. If you're losing you should keep quiet. But if you're winning you should shout "CHEEEEEEEEEEEEEEEEEEEEEEEEEECK" as loud as you can in your opponent's face.
Is it rude to announce "Check" in OTB chess?
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Life is too short to play a 1038 player two games in a row. On the main issue, I never announced check when I played tournament games, not because I'm polite or impolite or rules-abiding or disabiding, but because I am lazy, and I preferred to project the demeanor of a cold-blooded predator like a croc or a lizard, rather than a hyena. I don't care what my opponents do, as long as they don't do it in early Jim Carrey "Ch-ch-ch-ch-ch-ayyyyyyyukk." I will announce when I am teaching someone and they have had only several days of exposure to the game.