If nothing you ever did was good enough for your mother, than you'll know the tyranny of the whisper number. Traditionally, companies are judged by the earnings they report every quarter. Wall Street analysts guess at the revenue and profits (or losses) a company reports, and people buy and sell stocks based on whether they exceed, hit or fall short of those numbers.

Sounds like a simple formula, but some investors and traders can't be satisfied. During the tech boom of the 1990s, companies were judged not by how they performed against the official consensus estimates, but by a phantom number that analysts and hedge funds talked about among themselves.

Naturally, the whisper number was always higher, and companies that beat their earnings estimates by 2 cents could be punished for not beating them by 3 cents. Then again, to the analysts, credit, companies notoriously talked down their expectations, and cajoled analysts into lowering their views, in the hope of reporting better-than-expected results. So, whisper numbers often were a more accurate view of what numbers Wall Street thought a company should report.

Whisper numbers, even today, can be frustrating to regular investors. You wake up in the morning, Company XYZ reports earnings that seem to be on or above target, but the shares sell off. So, what do you do? Best advice: Ignore the whispering and focus on your own expectations.