He finds the zipper pull on the back of the sleeping bag. It feels like it's in the space between your legs behind your balls before your anus. He pulls, the zipper moves up your butt crack and up your spine to between your shoulders.
"Heh, of course," laughs your spandex loving friend, "It doesn't open all the way - it is a zentai sleepsack, isn't it. It's shaped like me, and will stretch around me." He strips completely naked and then he puts you on. He tries putting in a leg first, then decides he needs to get his head and torso in first. Even with the opening in your backside, it's a stretch to fit all 6'2" inches of Jamie inside you.
"Oh, good there is a zipper on the inside too, now to zip myself in and go to sleep," Jamie says as the zipper closes.
He bends his knees and lies down. He can see dimly through your fabric, as he lies down on the inflated air mattress.
"Oh, yeah, this feels great!" he shouts as your fabric caresses him, and you moan softly.
Soon he's erect, and half asleep. He yawns a satisfied yawn and dozes off.
He never did call you Matt, just friend. Does he know it's you? Or is he just excited to be using a living zentai sleeping bag or sleepsack or whatever? You feel his warm breath inside your face. It's getting damp where his mouth is drooling. It's also getting damp in the crotch area. He's leaking pre-cum. Does he know it's me? you wonder. You are feel like your shrinking around his sweating body. You feel yourself slipping between his butt cheeks. You cannot help yourself, it's what you are designed to do.