Source: Bulletin 1; 52nd Gold Coast Congress 2014 2014 Gold Coast Official Site
During a tournament in the USA back in the 1970s, it was quiet in the ballroom where the Life Master Pairs was in progress. All of a sudden, a baby let out a big wail. One player muttered, “Somebody just saw the dummy.”
You don’t want that to be your partner, but if the two of you are not on the same page with your takeout doubles, it could be. The best way to make sure you don’t give partner heartburn in that way – or suffer it yourself – is to make sure you are using the takeout double properly. This is a prime item for your Have You Discussed? agenda.
I have lost count of the number of times I’ve seen players double an opening bid for takeout with the wrong shape – that is, without support for unbid suits – and when someone looks askance at dummy, they say defensively, “But I have an opening hand!” Wrong, wrong, wrong. Suppose you are dealt
A 6 5 
K Q 5 4 
3 2 
Q J 8 7
and your right-hand opponent, the dealer, opens 1. What is your call?
If you selected pass, you might not need to read the rest of this article. Too often, I have seen players double for takeout with hands such as this.
All is fine if partner bids 2, but what if partner bids 2? Do you want to put that hand down as dummy? How
will partner like it if his hand is :
J 4 3 2 J 6 5 K 7 6 4 K 3?
But, you say, “If partner bids 2, I’ll just bid 2NT.” Again – Wrong, wrong, wrong!
When you double and bid notrump over partner’s response, you are showing a balanced hand too strong for a 1NT overcall, which I recommend to show 15-18 with a stopper in the suit that was opened. Doubling and bidding notrump is like opening one of a suit and rebidding 2NT when partner responds at the one level.
If you don’t have an agreement about doubling and bidding notrump, how would you ever describe a balanced 19-point hand when RHO opens at the one level? If you can overcall 1NT with a 19-point hand, how will partner ever know what to do with 6 HCP? If he passes and you have the 19-pointer, you probably missed game. If he bids on and you have the 15-pointer, you’re probably too high.
Back to the original hand. You must pass because you don’t have the right shape for making a takeout double, but suppose LHO bids 1NT, partner passes and RHO bids 2. Now you’re in business. You can double 2 to show that you have an opener (or close to it) and support for the unbid suits. It’s good that you want to compete, but you must be disciplined when your hand is not right for a takeout double.
Partner won’t be happy to see a singleton or doubleton in the suit he picked after your bid promised support for the unbid suits – and over time he will start to hold back and not bid the full value of his hand for fear that you will produce an unsuitable dummy.