Trade Me says there's been a large jump in the number of Christmas gifts being listed for resale.
Almost 12,000 items have been listed since 4pm on Saturday, an increase of 20% on last year.
The most listed item is women's clothing, either because it's the wrong size or the wrong colour.
Trade Me says there are also many chocolates and plenty of cosmetics and jewellery.
Trade Me says people seem to be listing things quickly so they can get some cash.