Poor Bridge

  S: K 7 4 3
  H: A J 5 3 2
  D: Q 5

  C: 8 6
 S: A Q 8 5 
 H: 6 
 D: 9 6 4 2 

 C: T 9 7 2 
NORTH  S: T 2
 H: Q 9 8 7
 D: K J T 8 3

 C: A J
W
E
S
T
6D
E
A
L
SOUTH
  S: J 9 6
  H: K T 4
  D: A 7

  C: K Q 5 4 3


 West     North    East     South
 John              Jonathan
                    p        1C
  p        1H       p        1NT
  p        2C       p        2H
  end
 (down 1, NS -50)

 West     North    East     South
          David             Toby
                    p        1NT
  p        2D       p        2H
  p        2S       p        3H
  end
 (down 1, NS -50)
N-S were playing a weak no-trump, but South chose to bid 1C on a balanced 13-count, and rebid 1NT despite holding heart support. Fortunately, they were playing a convention designed for just this situation - 2C was "Crowhurst", asking how many times South had misbid. 2H meant "I should have opened 1NT and I should have raised hearts". Useful.
Jonathan led the DJ from KJTxx. Seeing Ax in dummy and Qx in his hand, declarer found the avoidance play of rising with the A, and leading a small diamond to the bare Q! Jonathan won and switched to the T of spades, covered by the J and A. I played the Q, and declarer won. He cashed the HK and led a heart to the J and Q. When Jonathan returned a trump, declarer was stuck in dummy. He tried the 9 of spades, but Jonathan ruffed in and led a diamond.
Here David overbid and Toby ended up in 3H. The CT was led, and Toby read this for a doubleton, and decided to play the person with supposed short clubs for the HQ. Fortunately, he forgot who this was, and won HA and finessed the T. When West showed out, Toby realised that this made East 4-4 in hearts and clubs, and therefore short in spades, so to cater for any singleton he finessed the 7. East switched to a diamond, so Toby rose with the A and cashed the CQ, pitching a diamond, and was shocked to see it get ruffed. He should have cashed the HK first, just in case, but the defender "marked" with shortage had no trumps left. Now East crossed to the SA and got a spade ruff.
A "non-fit-non-jump"

  S: 7 4
  H: K 2
  D: A 9 8 5

  C: Q J 7 4 3
 S: K Q 8 6 2 
 H: T 9 8 
 D: T 6 

 C: 9 8 5 
NORTH  S: T
 H: Q J 7 5 4
 D: K Q J 7 4

 C: A T
D
E
A
L
8E
A
S
T
SOUTH
  S: A J 9 5 3
  H: A 6 3
  D: 3 2

  C: K 6 2


 West     North    East     South
 John              Jonathan
  p        p        1H       1S
  2H       3C       x        p
  3H       end
 (making, NS -140)

 West     North    East     South
          David             Toby     
  p        p        1H       1S
  2H       3C       4H       end
 (down 2, NS +100)
Double was a game-try, on a hand not suitable for 3D (=I have losers in diamonds).
Defence gave us the contract by leading Ace and another spade!
Systematically, 3C is a fit-non-jump, with spade support. 74 doubleton is not ideal :-)
4H is agressive and was fortunate to cost only 1 IMP as 3H would have gone off.
Good and bad auctions

  S: 7 5 4 3
  H: A 8 7
  D: A J T 9

  C: 8 4
 S: A 
 H: Q 9 5 3 
 D: Q 7 5 4 

 C: A J 9 2 
NORTH  S: K J 6 2
 H: K J T
 D: 2

 C: K T 7 6 3
W
E
S
T
18D
E
A
L
SOUTH
  S: Q T 9 8
  H: 6 4 2
  D: K 8 6 3

  C: Q 5


 West     North    East     South
 Toby              David
                    1C       p
  1H       p        1S       p
  2D       p        2H       p
  3C       p        3H       p
  3S       p        4C       p
  5C       end
 (making, NS -400)

 West     North    East     South
          Jonathan          John
                    p        p
  1D       p        1S       p
  2C       p        3NT      end
 (up 1, NS -430)
The Good Auction. David chose to open his hand, and Toby has enough to be thinking about slam chances. After fourth suit forcing got a 2H response, Toby could count 12 non-diamonds in David's hand, and so 3NT was not looking good. 3C is game-forcing, and after a couple of cue-bids, they wound up in 5C, which just relies on picking up the CQ.The Other Auction. At our table, East really didn't rate his hand, neither opening it nor making a 2-over-1 response. 3NT can be defeated (even if declarer picks up the clubs) on a diamond lead, but I chose the natural H4. The bidding and dummy mean that EW have at least a double heart guard, so after winning the HA, Jonathan should have tried a diamond switch. This would have been too late; my only entry is the DK and I need to lead through dummy twice.
Toby points out that the situation would be more amusing if South had the 9, West the 8 and North the 7; N could either return the 7, killing South's entry, or the J, which would eventually promote the 8 in dummy.
A Crazy Convention

  S: K T 6 4
  H: K Q 6 5
  D: A 6 5 2

  C: 2
 S: A Q 9 
 H: T 2 
 D: K T 7 4 3 

 C: K 5 4 
NORTH  S: J 7 5 3
 H: 8 4 3
 D: J

 C: A J T 8 7
W
E
S
T
19E
A
S
T
DEALER
  S: 8 2
  H: A J 9 7
  D: Q 9 8

  C: Q 9 6 3


 West     North    East     South
 Toby              David
                             p
  1NT      2D       p        2H
  p        p        2S       end
 (down 1, NS +100)

 West     North    East     South
          Jonathan          John
                             p
  1NT      end
 (down 2, NS +200)
2D showed a black singleton! Presumably it must be a three-suited hand (so as to be a legal convention), but as Toby said, "I don't care whether it's legal, I'm happy for them to play it against us!"
If you must play some sort of three-suited defence, recommended is Cansino, where 2C=3-suited with clubs, 2D=majors.
The lead was a club, won by the seven. David finessed the SQ. North won and switched to a heart for South to give him a club ruff. Another heart switch and club ruff and the DA were sufficient to beat 2S.
Against 1NT we took four hearts ending in my hand. I led the DQ to pin dummy's J, covered by the K and A. Jonathan led another diamond to set up my winner. Declarer played K and another club, and seeing Jonathan show out she should duck to set up the suit and preserve the entry, but she won the A and lost the spade finesse, and I took my top club and diamond for down two.
Frosty the Snowman

  S: K T 8
  H: A 4 2
  D: Q T 8 2

  C: A 8 7
 S: A J 2 
 H: K T 8 3 
 D: J 3 

 C: J 5 3 2 
NORTH  S: Q 9 6
 H: Q 9 6 5
 D: A 9 7 5

 C: 9 4
D
E
A
L
20E
A
S
T
SOUTH
  S: 7 5 4 3
  H: J 7
  D: K 6 4

  C: K Q T 6


 West     North    East     South
 Toby              David
  p        1NT      end
 (making, NS +90)

 West     North    East     South
          Jonathan          John
  p        1NT      end
 (up 1, NS +120)
David led the H5, covered by the J and K. Toby definitely wanted to continue hearts, and normally with three cards left he would lead the lowest to help partner count the suit. However, seeing the 7 in dummy, Toby realised that declarer might have started with A942, and led Frosty the Magic Snowman (aka the eight of hearts) to ensure three tricks in the suit.
Some confusion occurred when Toby then played low on the third round ("I wanted to keep the ten for its sheer power") and David was worried that declarer might have it (which admittedly would make his play at trick one bizarre).
I can't remember what happened at the other table...