Background Pony #51DE
I managed to track down the "source of the image":
http://item.taobao.com/item.htm?spm=a230r.1.14.23.52f3417bFfpOm5&id=635698158548&ns=1&abbucket=2#detail
http://item.taobao.com/item.htm?spm=a230r.1.14.23.52f3417bFfpOm5&id=635698158548&ns=1&abbucket=2#detail