One in four Americans admits to "re-gifting." Jerry coined the phrase 10 years ago, giving the age-old practice of repackaging unwanted presents its own name.

Re-gifting has become a big business for online auction sites like eBay.

In a new eBay survey of more than 500 Americans, more than half said they've re-gifted presents they didn't want. And 11 percent of those surveyed said they now sell those Christmas clunkers online.

"Just huge amounts of new sellers coming online to the sites with their gifts to resell. It's just becoming a broad, broad market," said Marsha Collier, author of the book "eBay for Dummies."

The kind of items people choose to sell are equally as wide.

For instance, one ad from a mother in Southaven, Miss., showed a green guitar her daughter didn't want. It's "fabulous if you ask me," the mother wrote.

Another ad from a woman in Lexington, Ky., was for not just one but 11 unwanted gifts.

She wrote, "My relatives must not like me. I thought one present was bad, but when you get 11 of them, something is up."

But what about the Christmas spirit — and the guilt involved in selling what someone gave you?