You open a letter that tells you that you've won a huge about of money in a sweepstakes you don't remember entering. Just send some money to cover taxes and fees and those riches will be yours.
You're a winner, but only if you toss that piece of mail in the trash. Sweepstakes scams come in many shapes and forms and we all want to believe that fortune has smiled upon us, but it likely hasn't. Particularly if that letter is postmarked standard presort -- a class used primarily for bulk delivery.
But whether it's a letter, a phone call or an email, check things out carefully and don't give in to wishful thinking. It could cost you everything you own.