Ken Eichenbaum described to me a cue concept that makes some sense. I recently saw a post on the BBF that illustrates where this would make a lot of sense. The idea of a WAC is that an "impossibly negative cue" is actually an "absolutely positive cue," showing stuff everywhere with uncertainty about passing the game level.
Here's an example.
How on earth can Opener have a 4D cue? No black suit controls at all means at best (in HCP) QJ-QJ. To even have a 2C opening, Opener would almost need solid diamonds and solid hearts. Sure -- possible. Kind of a picture jump without the jump. But, really? Why not simply bid 4H with that four-loser hand? Or, bid 3NT and then 4D if partner bids 4C?
Well, maybe this call (one under game), when impossible (or practically impossible) should rather than DENY any club or spade control actually PROMISE control in every suit (with slam interest) but express uncertainty about the five-level. In other words, if a cue denies "too much," then it instead promises "all."
The problem presented was after a 3S cue, a 4D cue from Responder, and a 4H "signoff" by Opener, could Opener have a club control but not enough cause to enter the five-level. If so, then Opener can never check on a club control and yet assuredly stay at game if this is denied. If not, then Opener is in a pickle with controls everywhere but not enough general strength to justify entry to the five-level.
The WAC grabs all and solves this problem (or possible/perceived problem at least).
Funny thing is that this concept first was presented to me as a result of a humorous analysis of a bizarre cuebidding decision. Someone (who shall remain nameless) made a cue in a specific sequence that seemed impossible. A technical hand was possible, even if that seemed really unlikely. So, as we are prone to do, we decided that this might make sense if the person thought up and launched without discussion (as we sometimes do ourselves, admittedly) a "new concept" that "just had to be obvious." In reality, it was just a bizarre call, a decision to cue for the first call and then jump into an undiscussed pattern bid for who knows what reason. But, every once in a while an absurd call out of the blue can serve as a discussion point for some actually relevant idea.
Of course, a good idea is to discuss (if you like the WAC idea) when this should apply. For, a call that is "impossible" is rare. More often, the call would be "highly improbable" or for obscure reasons actually redundant. This specific sequence of a one-under-game-initial-cue after a 2C opening and a 2-3 raise of a major seems fairly "impossible." But, whipping this out mid-stream, unless you are into that sort of thing, would be somewhat unwise, I suppose.