Test subject.

Ginny Weasley sat alone at a desk in the Hogwarts library, flipping through a stack of enormous textbooks, taking notes and occasionally groaning to herself. Romilda, Lavender and Parvati crouched behind a nearby bookshelf, watching and whispering to each other.

"Why her? Why can't we just use the potion on Hermione?"

"Fred and George told us to try it on Ginny first," said Romilda. "They said they always test their pranks on Ginny."

"I don't have anything against Ginny."

"Me neither, but I want to make sure it works. Anyway, be quiet. She's drinking it."

A can of soda sat on Ginny's desk, next to the books. Unthinkingly, she picked it up and took a sip. Romilda smiled.

"Fred and George's suggestible soda," she said. "If it's done the job, I should be able to control her body with my thoughts alone. What should we make her do first?"

"Jump up and down," suggested Lavender.

Ginny stood up. Surprise showed on her face as she began to do jumping jacks, the sound echoing in the quiet library. Parvati smirked as Romilda furrowed her brow in concentration.

"The signal's still weak," she said. "I'm going to make her drink the rest of the soda."

Ginny picked up the can of soda and gulped the rest of it down. She replaced the can on the desk and glanced to left and right nervously, not sure what was going on. "Hello? Is anyone here?"

"I think we can say it works," said Parvati.

"This isn't some kind of prank, is it?"

"Maybe. But I still want to be sure I can make her do something she doesn't want to do."

Ginny began to unfasten the first button on her blazer.

"This seems mean," said Lavender.

"We have to test it properly. Anyway, it's only Ginny."

The blazer was neatly folded and laid on the table next to the books. Soon, it was followed by Ginny's shirt. A blush began to blossom in the cheeks of the dishy redhead as she slipped her skirt down over her hips and kicked it off her ankles. She picked it up off the floor, folded it and set it down on top of the shirt before standing to attention in the middle of the quiet library, wearing nothing but her shoes, socks, bra and panties.

The door swung open.

Light shone into the room, and half a dozen students walked in, arguing and chattering among themselves. A Hufflepuff boy looked up just in time to catch a glimpse of Ginny's panty-clad bottom as she darted behind another shelf, face flaming, suddenly very conscious that she was trapped in a public space with nothing on but her underwear. Romilda, behind the first shelf, watched with interest.

"Hey," said the Hufflepuff boy. "Whose clothes are these?"

"Is there someone else in the library?" said a Hufflepuff girl.

"Are they naked?" said a Ravenclaw boy.

"Merlin's beard," Ginny muttered to herself, unaware that she was being spied on. "Fred, George, I'll have your bollocks for this." She crept slowly along behind the bookshelf, trying to get to the exit without being spotted. Romilda smirked as she watched her go.

"This is fun, isn't it?" she said. "But you're not getting off that easy."

Ginny was almost at the door when her hands suddenly, of their own accord, drifted behind her back. Romilda nodded in satisfaction as the unfortunate redhead was **** to unfasten her bra, which she left tucked into a heavy volume of Hogwarts: A History. Her strawberry-nippled breasts hung free as she hooked her thumbs into the waistband of her panties, cheeks burning red, biting down on her lip to prevent herself from making a telltale sound. The other students were right there, only a shelf away. But that didn't stop her from peeling the panties down her legs and stripping herself completely naked, right there in the library.

"So mean," said Parvati.

"I guess it's pretty funny, though," said Lavender.

Clutching her panties in her fist, Ginny cast a despairing look at the exit. It was only a few short steps away, but those short steps were out in the open, in full view of the other students, if any of them should turn around. They were looking this way and that, peering behind shelves in hopes of finding the naked girl. It was only a matter of time before they found her, and then she'd be totally humiliated. She had to take the risk. Concentrate on getting out of the library with her dignity intact, and after that she could work out how to get back to the dorms without anyone seeing her. And maybe how to get **** on Fred and George.

She summoned up all her courage and dashed out into the open. The door was right in front of her. But instead of going through it she stopped, turned around, put her panties on her head like a hat and shouted in a loud voice, "I'm Ginny Weasley! Everyone look at me!"

Everyone turned to look. Ginny stood there, naked from head to toe, from her strawberry nipples to the patch of red hair between her legs. She was blushing hotly, her eyes wide with astonishment at what she'd just said, wearing nothing but shoes, sock and the panties on her head. There was a long moment of silence, and then all the other students burst into hysterical laughter.

Ginny wanted to run. She wanted to squeal and cover herself and hide under the bed. Instead, she began to do jumping jacks.

"Wow," said Lavender, watching the fun. "That looks like absolute ****."

"I'm Ginny Weasley, and I'm a naughty girl! Watch my titties bounce!"

"Right. And it's nothing compared to what we're going to make Hermione do."