Careless Talk by Foxymoron

There is a tendency among top players to play that a double of 1NT is not for penalties. The opponents will often run somewhere if one has a weak hand, as will our partner of course. Equally importantly you will be telling the opponents that you have, say, 15+ high-card points. Careless Talk posters from the Second World War are collectors' items and sell for many thousands of pounds on Ebay. An example:

My partner did well to "keep schtum" on the following hand and reaped the benefits:

West opened a weak no-trump and North sensibly kept quiet. If he had doubled, then South would have been most unhappy. He would have been happier if he had a side bet on whether he would have been dealt a perfect Yarborough at the true odds of 1800-1, but otherwise he would have had nowhere to go. If East could redouble as "business" then North-South would be facing -1560.

After North passed, East bid Stayman which was his only way to invite game. West bid 2S and East bid 2NT. West was quite happy to accept and 3NT became the final contract. North led the queen of clubs and declarer can count seven tricks, two clubs, two hearts, two spades and a diamond. Not unreasonably he took two diamond finesses for his contract but the defence was now able to establish five tricks - two clubs, two diamonds and the ace of spades. One down and a top.

Schtum is one of many Yiddish words which have come into English, with several alternative spellings. Another theory is that it is prison slang. The earliest citation of it in print in English is in Frank Norman’s book Bang to Rights: an account of prison life, 1958:

“I think it’s much better to keep shtoom.”

“You can always shtoomup if any screws are earholeing.”