An old friend of mine and I several years ago had an auction that was a thing of beauty. It may have been insane. But, the fine line between insanity and genius is not for people like me to define. The auction was one where partner and I made "cuebids" not for the purpose of slam or game exploration, but for the defense.
The situation was one where we are white, the opponents red. We can take a sacrifice at six of a minor, which beats their red heart game, as we are down only three. The opponents can make five hearts unless we get off to the best defense.
So, the real-world results were varied, but the most common scores were 5minor our way, doubled for -300; 5H their way making 650 with normal defense; or 6minor our way, doubled for -500. Ideally, -300 looks great.
So, the auction. My RHO opened 1H, and I, with both minors, bid 2NT unusual. LHO raised to 3H, and my partner bid 4D. Opener bid 4H, to me.
I wanted to know which minor to lead. Maybe a club lead was best, but I had K-empty and did not want to spoil that card unnecessarily. Maybe a diamond was best, but I also had Q-empty there. Something like void-KJ-Q109xxx-K109xx. What to do?
Well, 5D seemed too lazy. I could try 4NT, which in theory should allow partner to pick the minor for lead, as 4D already set trumps, I figured. But, assuming a lead to partner, won by him, I wanted a spade back as an option to consider. So, my caqll was 4S, a cue for the defense.
LHO passed, which helped the plan along. Had partner no interest, he could bid 4NT. With a desire for a club lead, 5C. With confirmation of diamonds for the lead, 5D. In practice, his void in clubs screamed club lead.
The opponents would now be screwed. If they bid 5H, I would lead a club to partner's void, ruffed. He would lead back a spade, setting up a trick in spades. When he gets in with the trump Ace, the spade is the setting trick.
That was the only defensive line to beat 5H. The opponents, knowing that we had exchanged this info, would be forced to pick between a bad double and a worse 5H. Sure, we might panic and bid 6D anyway, not knowing that the defense would work, but we would be better set.
In practice, partner had no idea what I was doing and just bid 5D. Typical. Though, it is hard to blame anyone for not living in my world constantly, and he usually kept up with my insanity/genius.
That said, don't forget opportunities to cue for the defense. My partner, Ken Eichenbaum, recently trotted out a 5C call in competition for a club lead-director, which put a screeching halt to the opponents' thoughts of bidding 5S. A club lead to his stiff Ace would have primed us for a juicy defense, a defense I would not otherwise have found.