During the round robin of the 1985 World Team Championships (contesting the Bermuda Bowl) Canada played Bermuda. The latter team wasn't one of the favourites (to put it mildly).
The following deal turned out to be a nightmare for the Bermudian South — whose name wasn't mentioned in the original report; sadly enough it is common practice in bridge 'journalism' not to mention the name of a player who makes a mistake... Anyway, because of this deal he probably lost a lot of sleep over many years. Sometimes one wishes that one could go back in time in order to do better. This certainly was such a case.
This was South's hand:

¹ Artificial, 16⁺ HCP, any distribution
² Transfer to diamonds
³ Showing some values, not a penalty double (though South is of course free to pass)

True: South could pass. But West would bid 5♦ then and if North passed, South would have the same bidding problem. And if North doubled after some hesitation, South probably couldn't pull the double in view of ethics. So South did best by deciding now whether he wanted to defend or try for a slam.
This South player thought along these lines and didn't like any fuzz. He liked to get on with it. He realised that West had disclosed that North very probably had little or no strength in diamonds. So all face cards that North did have, were valuable ones.
And thus, hoping that North had at least three clubs, South bid 6♣.

This was followed by three passes and West lead the ♦4. Dummy was a dream come true:

The 2001 final of the Dutch Meesterklasse ('Master League', the top league) for teams.

Modalfa (Amsterdam) plays De Lombard (Rotterdam), contesting the Dutch championship. Any Amsterdam-Rotterdam encounter is characterised by intense rivalry, like Ajax - Feyenoord at football (soccer).
Noteworthy is that in that year's final all of the contesting partnerships were new: none of them had been playing in the Master League for longer than a year. Perhaps that is what caused the disaster below (by the way: Muller — De Wijs, to name one of the pairs, still play as a pair today, in 2010; so maybe some things have changed.)

The 1989 European Championships in Turku, Finland, Great-Britain vs. Austria.

Englishman Tony Forrester (photo), then already a world class player (he still is, so he is at the top for decades now), deliberately underbid, giving the opponents all the rope they needed to hang themselves.
Of course, with hindsight it is easy to say that the opponent in question should have known better. But it is the hallmark of the real crack to recognise opportunities in which he can make life miserable for his opponents.