I did like Steve's guesses (JPG photos) and I'd say those were correct as well.
But here is the real solution, as displayed by a somewhat overweight and out of shape model.
It's the Hawaiian shirt I was wearing yesterday. To the mystery solver who said it was a Tommy Bahama shirt, I'd have to say I don't think so. Good Hawaiian shirts are made with the patterns meeting perfectly across the fronts. As you can see, this is kind of a mish-mash.
As for those who suggested it might be some type of seat cushion, I think you've been conferring with Blackwell, who occasionally climbs on board my reclining figure and kneads my ample tummy.
Thanks for playing along!