Few minutes after that little "accident" you all returned to the train but you couldn't help but shudder in the sudden feeling of doom, when the train ended in a new station Celly called you three to the Bladder Tour, upon arriving the bladder you couldn't help but stare in awe, the bladder itself was a giant spherical chamber with mutiples tanks of urine and some other Liquids you can't identify, mutiples tubes transporting the urine are connected to their respective tanks while other liquids you can't identify going in similar way but they are connected towards the bladders' organic walls.
"Welcome to the Bladder Refinery!" Annouced Celly. "This organ is completely redesigned by Celestia to store different forms of chemicals and other liquids for Celestia' only use. You see the tubes going in and out they are store in different parts of the body, the moment that the princess feel the use of these chemicals, you see, unicorns or alicorns who feels the need to use a transformation in perfect sense they segregate these sames chemicals from their skin, here is different, here are in order.
"well, this refinery sure is big, I notice that, how many are here?" you said refering to the chemicals, as you all walk in organic catwalks above the tanks, for some reason a tank was calling your attention, it's green and bubbles come out of it
"Oh, that's what you're seeing is a potent form of acid capable to desintegrate everything in 5 seconds." now you're scared in going any close, while stomach acid can't affect you this acid probarbly has magic infused, however Celly was looking at you with a insane smile, the same smile that only monsters do upon seeing their prey.
"and is the perfect one for you" she said with an insane glee, neither Twilight or Luna doing nothing but stare, twilight has a paniked look but Lunas has an emotioless one, like she was especting something. Celly use her magic to lift from the catwalk, you use your own to cast an levitation spell but notice that you can't cast any magic, now you were completely scared, you grab a tube for support but her magic is too strong. You ask why she doing this.
"This is my revenge for that little stunt you pulled in the Spleen!!" you loose you support and fall in the green tank, the last thing you heard was Twilight yelling your name and Celly's insane laught...
... or that's what you thought as you float on surface completely intact, this is acid? you thought incredully.
Celly was rolling in the flood laughing madly while Luna bring you back to the catwalk, Luna couldn't too but giggle while twilight's eye was twiching madly. you look at celly angry but confused as well. angry because of this prank, confuse in why the acid didnt kill you.
"This acid is very speciffic one, it don't consume flesh but... clothes..." Celly ended while blushing furoiusly in your naked form, you notice that too and try to cast some clothes quickly, it was useful spell for travels but unfortunaly you can't do magic something that alarmed and confused you until Twilight cast some clothes for you, you thanks to her but you see her and Celly with bright blushes while Luna's whistle and lean to the mares.
"He sure is big..." she add with a chuckle making the mares even more red than before, meanwhile celestia outside chuckle at her avatar's fortune and twilight's misfortune
"Maybe we should continue with Womb Tour" Celly regaining composure this confuse you.
"but what about the Kidneys?" you ask.
"The Kidneys are the only organ that the princess hadn't changed yet except for the creation of these chemicals also, isn't recommended to go there for safetly reason." you nodded and follow Celly to an elevator that go to the womb, Twilight still in shock, her eyes twiching, Luna rolls her eyes and drag her with magic.