We live in a day and age where the stock market is mainly controlled by super computers. In fact, high frequency trading done via the computers makes up the vast majority of the volume on a daily basis.
While attempting to do some after hours trading, I stumbled across one of these computers trying to take advantage of me. I put in a sell order, and then all of a sudden, I was no longer the best offer on the ask (I wanted to short). I adjusted my order to be the lowest sell price, and then BOOM… again, I was no longer the best offer. Because I realized what was occurring, I decided to turn the table and take advantage of the computer and turn it against itself.