The California Lottery has a warning for players buying scratch-off tickets. They say you should check to see if the ticket has been tampered with. It works by stores scratching out a tiny code at the bottom of a scratch-off ticket and then entering that code into a lottery computer to determine if the ticket is a winner. The merchant then cashes in the winning tickets and leaves their customers with the losing ones. Check that your ticket has no numbers revealed at the bottom of your ticket - better to be safe than sorry!