Why is Willow naked?

Her wild, Wiccan ways

"Actually I'm what the old school witches used to call 'skyclad'," said Willow. "As in wearing nothing but the sky. You see, there are certain Wicca rites that can be performed in the absence of clothing and -- Hey! You never said why you were naked! Did you turn Wiccan too?"

"No," said Buffy. "I apparently got hit by a spell. Or a curse. I can't tell which. All I know is that whatever it is prevents me from wearing clothing. If I ever tries to put something on, it causes me great pain and I have to take it off again."

"It sounds like a curse," said Willow. "Which is weird because I was reading up on curses just the other day in a book written back in the 1950s by a Professor John Holden. From what I gather, they can be rather tricky to deal with."

"So does that mean you can't help me?" asked Buffy.

"Sure thing, Buffy," said Willow.

Then Willow paused and said, "Perhaps I can wait a while. For solidarity's sake. I don't want you to feel bad because I get to wear clothes and you can't, Buffy. So why don't I just wait here a bit and --"

"Oh, please," said Buffy. "You're the most modest person I know, Willow. I know you're just dying to get dressed again and quite frankly, I think my own nakedness is distracting enough without having to look at yours as well."

"Thanks for the compliment, I think," said Willow. "Let's go inside and do some research."

"Whatever you say, Knowledge Girl," said Buffy. "Just lead the way."