In practicing for Philadelphia with my good friend and partner, Ken Eichenbaum, we have discussed a very unusual phenomenon, the second-round canape.
Here's a few examples:
You are dealt 4-5-1-3 pattern and a fairly decent hand. You open 1H and partner makes a forcing 1NT call. Without sufficient strength to reverse, you opt for the clear 2C call. Partner now trots out the "impossible 2S," showing values and club support. So, you launch back 3S, which we now play as showing four spades and only three (or possibly two?) clubs, but a maximum. A canape, in that your THIRD SUIT is longer than your SECOND SUIT.
How about another one? You start with 1453 pattern with extras. 1D, but then partner bids 1S, which causes you to slow the auction down a bit. So, you opt for a 2C rebid. Partner courtesy-corrects to 2D. You now bid 2H, agreed as showing 4H and possibly only 3 clubs.
Another. You start with 3145 pattern, extras, but not quite sufficient for a 2D reverse after 1C-P-1H. (You also spurn the idea of the tendency canape 1D opening.) Your 1NT guarantees balanced (2-3 hearts), and 2C seems unappealing. Not good enough to reverse because of the wrong stiff, but close. No problem! You have already discussed with partner that a 1S call is possible with this pattern. When partner bids something below 2D, you complete your pattern with a 2D call, again showing longer in diamonds than spades.
I'd bet there are other situations where the 5431 "second and third suit canape" approach might make sense, but this is a new thing, at least for me, that I find fascinating to develop.