The best example involved this plain suit:
Declarer quickly led the Q out of hand before East had any information other than trick 1. Holding Kxxx, he decided to duck erroneously, allowing declarer to pitch a loser from dummy.
Another interesting example involved trying for an overtrick, but it was so late in the day, it's impossible to recall. Perhaps the key to great bridge is to save any fatigue for (yawn) after the hands are played.