This 2009 trials deal featured exuberant bidding that was vindicated by poor defense (as is so often the case).

Vul: None Dir:South	J 4 K 9 6 J 7 6 5 K Q 5 3
Q 9 8 7 5 2 10 5 2 A 10 9 4		K 6 3 A J 3 2 Q 4 3 J 8 6
	A 10 Q 8 7 4 A K 10 9 8 7 2

West	North	East	South
	Larry		David
	Pass	Pass	1
2	Double	Pass	4
Pass	Pass	Pass

I'd have preferred a fourth heart for my negative double, but I didn't want to raise diamonds with only four (our 1 opening is Precision and can be short). As East, I would have raised Lawfully to 3, but in any case, David stretched to bid 4. This looks to be a hopeless contract, but it took only one defensive lapse.

West led his singleton diamond. David won in hand and played a heart to the king and East's ace. Back came the4. West ruffed with the 10. Now came the moment of truth.

Not realizing that the 4 was a high one (suit-preference for spades), West failed to switch to spades (which would have set up two defensive tricks in time). Instead, he laid down the A. That was fatal.

David was now able to throw a spade on dummy's clubs. Because West's 10 was gone, he was also able to pick up trumps. He guessed to lead dummy's 9 to finesse through East and lost no more trump tricks. For 420 our team won a nice swing when a partscore (imagine that!) was played at the other table.