Heh, I thought it was a joke as well. Turns out its the real deal (at least, the concept exists).

http://en.wikipedia.org/wiki/Hindenburg_omen

This is the kicker however:

“On the other hand there has never been a significant stock market decline in history, that was not preceded by a confirmed Hindenburg Omen.”

Kind of like shooting an arrow at the side of a barn and then drawing the bullseye around it.