Once upon a time, there was a lawyer who was told to see if farmers made for good witnesses. The lawyer did so, and found that while most farmers were honest men, and thus excellent witnesses, some farmers lied constantly. He thought about this for a while, and presently came up with a theory that he decided to test.

He found a farmer that was a witness in three different crimes, and told him that all of his mules, horses, and donkeys had been sucked up in a tornado, and died. The farmer was shocked, and became utterly depressed, but still wanted to take the stand.

The next day, he told the farmer that he was wrong - in fact, one of the donkeys had survived! The farmer instantly was in a better mood - still sad at the major loss of his livestock, but glad that at least something survived - and he was still willing to take the stand.

Then came the final legal case. The lawyer took the farmer aside, and told him that he had even better news - the donkey that had survived had just given birth to a baby donkey - at which the judge immediately dismissed the case.

It turns out that the farmer was bi-assed.