Good LORD! Are you holding on to its tail? How else are you keeping it on your shoulder? This might be a L.A.M.E. photo, but that isn't a TAME Possum is it? (if so, why is it hissing?)
I've encountered them at night, in South Georgia USA, they would hiss, then try to run, and if none of that worked, then they would "play Possum".
Tame or not, you got my upvote Wild Man @papa-pepper