The boat ride is probably going to take several hours, which would be way past midnight when it docks. You're getting tired anyway, sleeping now seems to be the ideal thing to do. You have a feeling you will need it, you're feeling the urge kicking in anyway.
"Ya-HAAAAAAAW-n..."
Your muzzle cracks into an earsplitting yawn. You rub it drowsily, tracing it up to your asinine face and down towards the rest of your body. You'll panic later, right now you're too tired to care. You go out like a light.
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Unconsciously, you wiggle out of your itchy, constraining clothes and kick them to the corner. Your expanding body ever so slightly gets overtaken by pelt and muscles, your limbs bulking up with the animalistic strength. Slower and slower the changes get, finally burning out the last of its magic, fueled by the enchanted hay, with a kick to your crotch.
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Your eyes snap open, braying pleasurably to a dream slipping away from your memory. You startles when you find yourself looking like a donkey-headed satyr, but you push that fact aside for more pressing matters. The boat is docked, and no one seems to be up and about, even the stalls are quiet. Everything seems to be sleeping under the night's covers, this seems to be the perfect time to leave.