Here's another hand from our Okbridge bird, Magpie, aka Marvin Eisner.
Opening Lead: Queen of Diamonds.
Let me guess how this would play out at most tables. Declarer would play K-A of diamonds and ruff a third round low. East would overruff and start hearts. Looking at two heart losers in addition to the overruff, declarer would eventually decide that he needed to drop the trump King and would lead a spade to the ace. Bonanza! He'd now be able to ruff his last diamond, get back to his hand with a club ruff and pull trump for ten tricks.
Things began exactly that way when Magpie was East...except that he decided to try the effect of overruffing North's deuce of spades with the King! Declarer now knew the exact trump distribution, 9874 opposite K. He played Ace of Clubs, ruffed a club, and ruffed his last diamond with the spade 3. When Magpie overruffed with the 4, he no doubt congratulated him warmly on his fine defense.