The communication between the hand and the dummy is very important for the declarer to succeed in various positions.
In contrast, the communication between the defenders hands is also essential, as is often necessary to enter partner’s hand so he can cross a certain suit, or for he to play his high cards or for he can play a certain suit for you to ruff.
An attentive declarer can see the problem and try not to give the hand to one or the other defender or “cut” communication between opps hands, applying a play technique called: “The Scissors Coup”.
This “coup” cuts the communications between the opps hands, by playing a suit which would have served as an entrance into one of the opps hands or pitch a suit to avoid a ruff from opps.
Lets see an example hand. East opens 1
and South finish playing 4
. Lead: Q. East overtakes the Q with the K and returns a 
. The declarer realizes that this move only makes sense if this is a singleton and he wants to use his partner’s J as an entry to ruff a club and defeat the contract.
The declarer must try to cut off communication between EW, but to this he must get rid of dummy’s , the entry East requires for his ruff.
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To do this, he must pitch dummy’s in the third 
, expecting West cant cover the 10. After winning the club with his K, the declarer plays to the K, to the A and 10, pitching dummy’s (loser over loser) – preventing W to win a trick and so guaranteeing his contract.