The free rental is a scam which makes use of the loose return policies of corporate retail entities.
While many people complain about the presence of monolithic turd factories such as Wal-Mart in their otherwise decent neighborhoods, they often fail to realize that these establishments can also be quite useful in certain situations.
To get a free rental, simply save your receipt after making any non-perishable item purchase from a retail giant. Make note of the time frame within which you are allowed to enjoy your purchase (this information is usually printed on your receipt) and then take it back for a cash refund prior to the expiration for that time period.
For example, the time limit for returns at Wal-Mart is 90 days, so one must return the item within that time to successfully complete the free rental.
It is also noteworthy that while Wal-Mart WILL accept returns without a receipt, the purchaser must allow their state-issued identification to be photocopied when this transaction takes place. Wal-Mart's corporate policy currently dictates that a maximum of 3 of these receipt-less transactions be allowed per person each year. Of course, this policy can easily be bypassed by any person who has access to fraudulent forms of identification, and/or a borrowed ID.
My mom couldn't afford to buy an air conditioner for her blazing hot, shitty apartment, so she rolled down to Fail-Mart to pick up a free rental window unit for the summer months. When the weather cools off, she'll probably return the AC unit and buy herself a nice warm coat from the same store. Oh wait, did I say 'BUY'? Silly me, I meant to say she'll get a FREE RENTAL!