Here's an interesting hand from Friday:
We had a relay auction where I showed a 5-1-3-4 distribution and GF opposite 15+HCP. I ended up playing 3NT by South, and LHO lead ♦K.
I thought it was a good idea to duck, since it's almost a real "bath coup". LHO switched to ♣ after considerable thought. It's quite obvious to play the T, for the Q and my King. The switch didn't matter much, since there's only 1 useful way to finesse ♣ anyway. Now I tested the ♥s: ♥K, followed by ♣A and 2 more ♥s. Both opponents follow nicely, so it's time to think about overtricks.
I was considering my squeeze possibilities, and played a small ♠. RHO played his ♠K leaving me no choice than to play my Ace. Now I cashed ♣J (LHO playing the 9) discarding a ♦, ♦J (covered) to the Ace and ran my ♥s. This is a simple squeeze played like a double squeeze, also known as an "Either-Or" squeeze. Whoever has ♠J will have to concede it, since LHO has to guard the virtual ♠Jx and ♦, and RHO has to keep the virtual ♠Jx and ♣. We don't care who we squeeze, but it works with both opponents.
Also interesting would it have been if RHO played small. Now there are 2 possible lines:
1. play the Queen, and if it works use a double squeeze to get to 12 tricks
2. play the T hoping for RHO having ♠KJx
Obviously line 1 is better. If RHO has ♠KJx he'll be caught in a simple squeeze later on anyway.
By playing ♠K my RHO gave me an opportunity to add this one to my list.