You follow the signs saying about looking for those interested in joining the circus, and it leads to a trailer, with an officer hours faux clock hanging outside that showed yes, they were open. There was brief forum to fill out that was on the side of the trailer, in a typical 'take one' plastic holder. It said 'inquire within once filled out'. The trailer's windows had the blinds down.
It asked name, sex, age, maternal status, closest kin, among other things and strangely favorite circus animal. This done, you used lion headed knocker on the door. "Hello? I'm interested in the job."
"Come on in please." Said a woman's voice with a Russian accent.
You walked in, and found a trailer with several stacks of paper work. And a naked leopard woman sitting behind the desk, well, not completely naked, she seemed to have colorful black light sensitive paint on some of her spots and a red sequined cape over her shoulders. "Well hello there."
"Hello." You replied. You should have been shocked and confused. Wait... hadn't you SEEN creatures like her on posters for the entire circus?
"Hello, my name is Alyona. Don't be worried that you're not worried, it's just the nature of the circus. If you haven't fainted or run away, that just means everything is normal. Let me give you our introductory speech, it feels better if we give it personally rather than a recording. People have been growing against circus' having animals for years... but there was a way around it. What if the circus had animals, wild beasts who performed for the joy of the audience, but wouldn't have animal rights groups trying to lynch us? This circus was on the verge of collapse, as animals had always been its specialty. But as it turns out, part of the trope either knew or found some rather potent power, nothing that could conquer the world, had some utterly insane restrictions, but it could help us. So we released all our mundane animals... and took their place. It's now standard to be part of our circus."
"And... if I want the job?"
"It's rather straight forward really. You turn into a nudist anthro animal, and become bound to the circus as part of a life time contract. You retroactively become one, which means as far as anyone will remember you were always part of the circus. You be basically an sapient beast that stands on two legs with thumbs, and people will see you as such, but they'll all unconsciously be aware you've chosen this of your own free will. You get eternal youth, freedom from all sicknesses, you get to be in show business, and everyone here will welcome you as part of our family. You're also entitled to a equal share in ownership of the circus. You brain will be that of an intelligent animal rather than an intelligent human if that makes sense to you."
"... Is it reversible?"
"What part of 'immortality, and lifetime contract' was hard to understand?"
"So one way eh?"
"In a word: yes. Trust me, once you hit thirty, you suddenly stop angsting over living forever."
"... I get to pick what animal I turn into?"
"From those we have a spot for. Let's see what we have-"