They charge extra for hog's guts in the form of "Premium, Natural Casing" hot dogs. Makes me wonder what they use for the skin of a cheap weiner. I can't see myself stuffing my face with just casings, though I might try them if somebody stuck them under my nose and they smelled good.
Always good to know how to render your own meat if you catch a "roast-on-the-hoof" taking a shortcut across your yard.
I don't think a squirrel brain would be worth the energy expended in harvesting it. Do people crack the head open like a walnut....or simmer it for hours until everything is soft enough to just come apart?
Have you tried tripe?