This is a preliminary line sometimes published to a select few prior to the publication of the official line.
Linemakers will invite specially selected players, usually professional gamblers and sharps who wager lots of money on sports, to wager on the outlaw line before publishing the line to the public. The linemakers only choose those individuals whom they respect and use their input to create a final opening line. This process is also known as ironing, or flattening, the line because the input and size of the bets helps the linemaker determine exactly the right line to publish. The outlaw line got its name from the early days of gambling, when it was illegal to do so. Prior to an official line being published, bookmakers would go to their professional gambler friends, who were outlaws as a result of their gambling, to gauge their response to the initial, unpublished, betting lines.