One hand that caused consternation during a recent class was this:
Your partner opens 1NT (12-14pts). What would you respond holding:
Before getting to the answer, I asked students what they thought the final contract would be? The answer, of course, is 4H.
Not a mis-print. Your partner has 14pts at most, you have 1. So your opponents hold 25pts between them - sufficient values for game. You have a 9 or 10-card fit in spades, therefore your opponents have a big fit in one (or more) of their suits. Since your partner shouldn't have a 5-card heart suit for her 1NT opening, you know that your opponents definitely have an 8-card heart fit. So, the most likely contract is 4H - by your enemies.
The best way to stop this is to bid 4S immediately. This will pile the pressure on to your left hand opponent. It is unlikely that you will be doubled for penalities, since you have so many spades between you and, even if you do, your shape should ensure that you won't go more than 2 or 3 down. Still, a good save against 4H making.
Don't use transfers; don't bid 2S and wait for your opponents to find a fit and then bid some more spades. Cut them out of the auction right NOW!
The most likely scenario is that your opponents will stare gormlessly at their cards for a while and both say no-bid. Then you will go quietly down and save yielding a game to your opposition.