Apologies to J. K. Rowling for this gender tomfoolery.
All Harry Potters are in their final year of Hogwarts and thus 18+
"Did you slip something else into the potion?" Harry giggled, glancing down as trampy tattoos blossomed over his tits. The more he drank, the dumber and hornier he felt. He cuddled closer to Ron, impatient to start fucking.
"What makes you say that?" Ron asked slyly.
"Because I'm really starting to look like that muggle tart you were drooling over at King's Cross," Harry pouted.
"Maybe I accio'd a hair off her, maybe I didn't," Ron winked.
"You realise it was just a sex-change polyjuice potion, right? If you added anything, I could be stuck this way a lot longer than Christmas," Harry sulked.
But he soon stopped his whining once Ron's dick was in his mouth, sucking it hungrily like the hooker whom he now partially resembled. Ron waited until he was about to climax before breaking the bad news.
"Maybe I shouldn't have added those hairs from Hermione's cat then..." he pondered aloud.
Harry's eyes went wide as his mouth begin to fill, a cat tail springing free from his pants.