You decide to volunteer as the snake's next partner, and snack, and raise your hand.
"Excellent!" The guide exclaims, and ushers you to the front of the small crowd. "Alright, now strip down, and Bobby and I will do the rest." You obey, blushing as you notice yourself becoming the center of attention while stripping off your clothes in front of a group of strangers, most of whom are your age, and many of whom are rather cute.
Fully naked, your cock stands half-erect as you step out of your discarded clothes, and the zookeeper takes them and simply dumps them into a waiting rolling bin. "Okay now, everyone," he says, and takes out a small bottle hidden in a compartment disguised as a rock, "watch Bobby's mouth when I open up the bottle." He does so, and you immediately feel the snake's tongue lash against your back. "These are pheromones of a female anaconda, and our volunteer here - what's your name, by the way?" "Alex," you respond. "And Alex here smells like a female anaconda ready to be bred!" The guide notes excitedly, earning a chuckle from the crowd.
The guide gently pushes you backwards, onto the slanted-up body of the snake, and you look down to see the snake's dick standing straight up. It's easily twice the size of yours, which also stands at full attention, and you briefly wonder just what you've gotten yourself into. The guide takes another bottle out of the same hidden compartment, and opens it, spreading a generous amount of lube onto his hands and then rubbing it on the snake's pink cock. You yelp in surprise as he takes two of his fingers and shoves them into your hole, and the crowd starts to laugh. It's more than a bit embarrassing to be manhandled like this, but you suppose it won't really matter for long. The zookeeper then guides the snake's cock into your lubed hole, and you gasp again as it penetrates you.
You sink slowly lower onto your predator's cock, and feel the cool sensation of the cold-blooded snake inside you. It begins to move faster, and you bounce up and down with it as it fucks you.
"So in this case," the zookeeper explains, "Bobby already knows that he's fucking something other than another anaconda in heat. Right now though, he's going through the motions as a predatory dominance tactic - prey items are less likely to escape if they're mesmerized by a good fucking, after all. Isn't that right, Alex?" He asks, teasingly, and you stammer out a "Yes".
The snake tenses inside you, its rigid shaft spurting out a cool substance, and you finally take a hand to your waiting, painfully hard cock and begin stroking furiously. After a moment, your eyes close tightly as a massive orgasm rocks your body, and your legs spasm then go limp. When you open your eyes, you see darkness, and you feel the snake's maw enclosing your shoulders. Its tongue wraps around your throat, and you go lightheaded as it helps pull you up into its body. Soon you feel your arms and pelvis follow you into your predator's gullet, and it quickly swallows up your feat to finish you off. You feel dizzy as the snake twists around, and you're unable to get your bearings before you feel through the snake's body, the coolness of its water pool.
Your head gets lighter, and you begin to feel the tingle of the snake's digestive juices as you fall unconscious, content with your final breeding.