A Muggle In The Wizarding World?!

Polyjuice Potion

Y/N POV
It was quite late at night as I went to the girls bathroom on the second floor. There I saw Hermione, Harry and Ron all perfectly ready. They were wearing the Slytherin's House Robes.  "So did you get it?" Hermione asked Harry and Ron. Both of them proudly held up tufts of hair each.

"I'm sure I've done everything right. It looks like the book said it should. Once we've drunk
it, we'll have exactly one hour before we change back into ourselves." said Hermione while stirring the potion. "Now what?" asked Ron.

"We separate the Polyjuice into 3 glasses and add the hairs." said Hermione.

They put their different types of hair they found and added it into the glass of Polyjuice each.

"Alright everyone in the count of three... one, two, three." They all gulped the juice down, Ron's face turned extremely unpleasant. "I think I'm gonna be sick." he said.

They all looked like that they were gonna throw up. "Guys, something's wrong with mine!" then Hermione ran off into the bathroom stall. Harry and Ron started to change. After a few moments, they looked exactly like Crabbe and Goyle.

"Woah, is that really you guys?" I asked in surprise to the two 'fake' Crabbe and Goyle. "Yeah. It's me. Bloody hell, is that you Harry?" said Ron/'Crabbe'
"Yes. But we still sound like ourselves. You need to sound more like Crabbe."
"Wow, I can't believe this actually worked!" I said. "Yeah. It's unbelievable right? Hermione, we're all ready, you can come out now." said Harry.

"I don't think I'm going. You guys go without me." Hermione called back from the stall. We went towards the stall she was in. "Hermione, are you okay?" Harry asked. "Just go! You're wasting time!" she answered back.

"Uh. Alright, see you there." They both replied and hurried off. Once they were gone, I pushed the bathroom stall open. and saw a very furry human being with cat ears. "Hermione. Is that you?" I asked.

Hermione looked up at us, " I think I got mixed up with a cats fur instead of Millicent Bulstrode's."
"Oh."
"Well, I'm sure that Harry and Ron will find out any more information on the True Heir of Slytherin without me."
Then a high pitched voice interrupted us, "You guys didn't forget I was here. Did you?"
"Um. Of course not." I replied.

...

After an about an hour, Harry and Ron dashed back into the bathroom calling "Hermione!
Y/N! We've got lots to tell you guys!"

"Go away."  shouted Hermione. Harry and Ron came to me and whispered, "Which stall is she in?" I pointed towards the stall. "Ooh, wait till you see. It's awful!" Moaning Myrtle said cheekily. They both pushed the stall door slowly and saw Hermione.

Both of their eyes grew big in shock. "Do you remember me telling you the Polyjuice Potion was only for human transformations...?" Even in the shadows, I can still see Hermione's face covered with fur. But her eyes and ears popped out through the fur. "It was cat hair I plucked off Millicent Bulstrode's robes! Look at my face!" cried Hermione. "Look at your tail." gushed Ron.