WeLoveFine.com sells that same RD hoodie on their site. I think they only offer women's sizes, but they go up to 2XL, so you might be able to buy one that fits? Here's the link: http://www.welovefine.com/2275-rainbow-face-hoodie.html
I also make RD hoodies with manes and ears, and I currently have a men's XL available in my Etsy shop: http://www.etsy.com/listing/103387445/my-little-pony-hoodie-rainbow-dash-x