Scared cats fluff out or tuck their tails and flatten their ears. They absolutely don't just casually expose their bellies. This cat is relaxed, if alert and ready for play.
I once had a “special” cat, too. I once heard her screaming for help, and found her standing with her front paws on the coffee table and her rear paws on the sofa. She was trapped there, less than 2 feet off the ground, and couldn’t figure out a way to get down.
Goofy is our cat's name also. She was a stray that would come in when I let the dogs in. I'd push her back out and say "Goofy, you're not one of our dogs!" We've had her 4 years now and Goofy just stuck and she's right at home in the house now.
Aw, cutie pie. He looks like he's seen some things. Or may currently be seeing some things. Might need to cut back on the nip.