If “The Twelve Days of Christmas” had been allowed to continue, the 13th would surely involve your “true love” listing all your unwanted presents on eBay. Just as no one needs 11 pipers piping, a pair of penguin-shaped slippers and a T-shirt with “All the Jingle Ladies” emblazoned on the front weren’t on our Christmas lists. Scrooges, the lot of us? Maybe. But according to research by eBay, Britons received 115 million gifts that didn’t hit the mark last year.