When you really want it to be for penalties but it just isn't

 In a recent online club game, I picked up the following not very promising hand: QT874 75 Q9632 6 as West. We were at unfavorable vulnerability and partner opened 2H as dealer. RHO doubled and I quickly passed hoping that LHO wouldn't convert to penalties. Imagine my delight when LHO jumped to 4S. No, I didn't do anything foolish like double. 

Partner led the HT and dummy came down: 5 AQJ2 AK85 A953. A fine hand. Just not for playing 4S. Despite my good spade suit, this was a surprisingly tough contract to set but we did get our 50 in the end. This wasn't quite a top, because at another table, after the same start, South pulled 4S to 6NT, going down two.

Three other tables began with 2H double. In each case, the North hand bid a more modest 2S or 3S and doubler was able to call 3NT, which should take eleven tricks, and mostly did. One table began with 2H followed by two passes. North, didn't cooperate but instead bid 2S, converted to 3NT. Note that 2H doubled would have been worth 1100 for N/S.

The par result is 6C for 920, which nobody found, not even those that didn't get a 2H preempt. 

Here is the whole hand:

So, how should the South hand act over the 2H bid? I think this is a clear-cut trap pass. First of all, if partner has some nondescript hand and decides to pass, we might not even have a game, in which case 200, 300 or 400 will be a fine result. But, if North has some useful values, we can be sure that he will act in some way. He probably has only one or two hearts which will make him want to do something. If that something is double, we will of course sit for it. We only need to get the contract down two to beat any game that we can make. But what if he has his own suit and decides to bid that. No harm done. We just bid 3NT. 

A trap pass such as this is one of the most satisfying situations in bridge--that is when partner comes through. It can fizzle of course if partner meekly passes. But, even then, all may not be lost.