It's the Classic Zooop Fleece Golf onesie from a company called Zooop It Up! They are makers of "luxury adult onesies."
The product page on the Zooop It Up! website suggests "Wear anywhere: beach, dancing, poker games ..." But hey, why not wear it to a golf course that doesn't have a dress code! Or at least wear it on your couch as you watch golf on TV.
The Zooop Golf Onesie is 80-percent cotton/20-percent polyester; it is hooded and footless; it has two front pouch pockets and two zippered pockets. And it's fleece.
"This ZOOOP iT UP Classic ZOOOP onesie unisex fit is perfect for him or her. Your search for the Ultimate Comfy Wear ends now. Once you've put on your ZOOOP you'll never want to part from it!"
So says the company. And who are we to argue? I want one, and if I get one I plan on blogging in it.