Bridge is a funny game. One aspect of it that is quite humorous to me is the Principle of Consistent Weirdness. This principle establishes that weird bids or plays have a tendency to induce further weird bids or plays. Remember this.
My favorite problem of this sort was in a suit contract. I was in Dummy, but I would opnly be back there one more time. In a side suit, Dummy held KJ109xxx opposite my stiff. So, with nothing better to do while over there, I decided to lead one of these cards toward my hand, ruffing and hoping for something good to happen. But, which card?
I could try the King, hoping to smother the stiff Queen. I could just play small, hoping for the stiff Ace or for RHO to hop the Ace. Or, I might even try the tricky Jack.
I tried the 10.
Why? Because the 10 is weird. And, by application of the Principle of Consistent Weirdness, the 10 was fhe most likely weird card to induce a weird card from RHO. Weird begets weird.
In practice, RHO hopped the Ace, I ruffed, and I later enjoyed the King. Did the 10 have any impact at all on this situation? Did RHO think I was being tricky with the stiff Queen? No. RHO started with both the Ace and the Queen. There was absolutely no reason to play the Ace rather than the Queen. Except, that is, that the 10 was so very weird that the PCW forced that Ace out of his hand.
The same thing happens, of course, during the bidding. However, be careful trying to whip out the PCW in the bidding, as partner has a tendency to be sucked into the weirdness vibe. The same can be said for PCW on defense -- be careful to ensure as much as possible that partner's weirdness cannot hurt.
Finally, if you check, you will probably find PCW principles at play with the opponents' convention cards. generally, people who play weird conventions play a lot of weird conventions. If you can only find one weird convention on their card, expect their seemingly normal sequences to in fact be weird nonetheless. Plus, if you see weirdness on their convention card, be quick to make the first weird bid, or at least a reciprocal-weirdness call, as this usually induces an equal reaction of enhanced weirdness from these opponents.
Don't get me started with directors.