Thank you, some person in Blogland that I can't remember because I am a blog-slut. I read your blog, saw your pictures and was bowled over by the obviousness of your ingenuity. I have you, Mystery Blogger to thank for this.
It's a dog collar / toddler belt / Indian headband. And every time I try to put it on D, it makes that jingly dog-collar-being-attached-to-leash noise which makes him call out for "No-men-o" (translate to "Romeo"), the contractors dog. He is a very smart boy and will undoubtedly be in therapy for being forced to wear doggie accessories when young.