My partner passed and RHO opened a weak NT (11-14 HCP). I held: ♠AJ4 ♥A4 ♦K1085 ♣KQ104 and doubled which is penalty-oriented against a weak NT. Partner is expected to sit with any eight or more HCP or a decent 7. With very few points, partner can bid a long suit if he has one. Otherwise, partner passes. -180 (1NT* making one) is not the end of the world! LHO asked my partner what the bid meant, and my partner replied “Penalty oriented.” LHO passed as did my partner. RHO then thought a long time and bid 2♣. Since that was the suit I was intending to lead against 1NT*, I was happy to double again and everyone passed. [Declarer could have five clubs, but most Weak NT bidders simply start bidding four card suits up the line in this situation, hoping to find a fit.]
I'm not leading an Ace without a King and I expect 3 natural club tricks anyway, so I'm not looking for a ruff. So, I led a fourth-best diamond and Dummy hits with: ♠K1087 ♥1092 ♦J3 ♣7652. Partner—bless him—produced the ♦Q and Declarer took the ♦A. She then played a spade to the ♠K (which I ducked) and a spade back to her ♠Q which I took. I took the ♦K, killing Dummy's the ♦J, and partner gave current count in diamonds, so I SHOULD HAVE KNOWN that partner started with four, and Declarer had one more, but I had lost track of the diamond spots, so I was unsure.
Stopping to count Declarer's points, I'm assigning the ♣AJ to her. We have seen the ♠Q and the ♦A. That is 11 HCP. If she has only that, partner could have both King and the ♥Q, but Declarer could still have the ♥K and partner could have the ♥Q and the ♥J. I decide to risk the ♥A. Unfortunately partner plays an ambiguous the ♥5 (standard signals) while Declarer plays the six. The ♥3 is missing, but I cannot be sure partner has it. (This Declarer is good enough to falsecard.) I SHOULD have played another diamond and just let Declarer ruff on Dummy (had I not lost track of the spots) OR played another heart because I have already given away a trick if Declarer has the King, but even then partner will have ♥QJ. Instead, I played my top spade and Declarer ruffed in her hand. She then ruffed a diamond on dummy and discarded a heart loser on Dummy's top spade as I ruffed. I then, belatedly led a heart to my partner's King AND Queen. (Both cashed because Declarer had started with four hearts.) Partner then played another heart, giving me an uppercut as I have ♣KQ10 remaining behind her ♣A98. So we got two of the last three tricks.
Turns out, double-dummy, I could have let a club to my partner's singleton Jack! Despite my missing out on the diamond spots, we got the eight tricks to which we were entitled without the double-dummy club lead. (Declarer will usually get two minor Aces; one spade trick; one diamond ruff in dummy and one spade ruff in her own hand as happened.) However, down 3 doubled for 800 more than made up for our possible game. In actual fact, most people would NOT invite game with my partner's hand. I would treat it as a “garbage Stayman” hand and bid 2♣ and then PASS partner's 2♦ response. [Partner's hand was: ♠9653 ♥KQ53 ♦Q964 ♣J.]