warner in bangladesh, noun
Something that is expected to fail dismally, but ends up doing very well
"Many aviators and engineers thought that the Wright brothers' aeroplane designs would never work, but history has shown that in this regard the designs were a warner in bangladesh."
And, going back a bit
play for turn from giles, verb
To assume something is going to happen, when it is actually very unlikely to
"Barney always had a tendency to rush into things, but he really played for turn from giles when he brought £10,000 worth of shares in Northern Rock, assuming that their value would rise, when the news was full of stories of it's impeding bankruptcy and collapse."