A ship's captain and chief engineer often argued about whose job was more important. They decided to settle their dispute by trading places for a day. After a difficult few hours, the captain called the bridge, where the engineer was at the helm.
"Chief," he wailed, "I can't make her go!"
"I don't wonder," was the reply. "I've run her aground."
At bridge, you're half of a partnership. Partners must rely on each other, not try to outdo each other.
Against today's four hearts, West led the ace of diamonds in response to East's overcall, and East signaled with the ten. West led another diamond, and East won and led a third diamond (the nine, a suit-preference signal to show spade strength). East hoped West could ruff, but South threw a spade as dummy's queen won. South then drew trumps and claimed 10 tricks.
"You wanted a spade shift," West told his partner. "Signal with the deuce on the first diamond."
"Wouldn't the deuce suggest a club shift?" East asked. "Besides, for all I knew, you had the doubleton ace of diamonds."
"Signal with your lowest diamond to ask for a shift to the logical suit," West persisted. "That could only be spades."
East signaled correctly. He had to encourage in diamonds in case West could ruff the third diamond. But East's ten denied possession of the jack, hence West could see that a diamond continuation would set up a winner for declarer. Moreover, West knew he couldn't ruff the third diamond.