When you give someone a gift, do you think it's OK for them to re-gift it or sell it online? U.S. News and World Report says that 70 percent of people think it's acceptable. Some 50 percent admitted to actually doing this. Clark believes there's nothing wrong with re-gifting or selling a gift if you don't want it. But be careful; he once actually re-gifted something back to the initial giver! So make sure you know who gave it to you before you go giving it back to them. When it comes to doing a return, retailers may require you to have a gift receipt because they're trying to crack down on internal theft rings. So when you give a gift, try taping the gift receipt to the gift itself -- not just to the wrapping paper. Clark's key rule about doing returns is do not go back to the stores until the first week of January. The return lines are maddening and the merchandise is actually pricey between Christmas and Jan. 1.