One thing I noticed lately since it is the holiday shopping that a lot of people throw away the secondary receipt that they receive as a result of a purchase. Essentially, this has information thanking you for shopping at the store and in many cases obtaining a discount code for future purchases. For example, there could be ones saying $3 off your next DVD or Blu-Ray movie purchase or even $10 off after spending $50.
Another interesting point is that many of these coupon receipts don’t even have an expiry date on it. Maybe it’s simply a force of habit for many as usually secondary receipts contain information to enter a contest or to partake in a survey. Check again before tossing those receipts as you could be throwing away free money.