I do not own Buffy, Ziggy Stardust or Starman. Don't sue me for their use.
This story isn't meant to be taken seriously. It also doesn't strictly follow the Ship of the Line challenge, but I found the idea too hilarious not to write, and it does (kind of) follow some of the criteria.
Xander didn't like music. That's not to say that he wouldn't listen to some if there was some playing, but he wouldn't choose to play anything of his own volition.
Buffy found that unbelievable, and so set about finding some music that Xander would voluntarily play. Both Willow and Xander doubted that she could, but Buffy decided to raise the stakes - if she succeeded, Xander would owe her a favour.
Buffy quickly found that Xander couldn't stand Classical. He didn't like Jazz. Rap left him cold. Punk made him laugh and think of Spike.
Then Buffy hit upon David Bowie, and Xander's world was never the same. He listened to his songs over and over. He particularly loved Starman.
Buffy didn't demand the favour from him immediately. She waited a few weeks, until a suitable moment came up.
It was just before Halloween that Buffy decided to call in the favour.
"Hey, Xander?" she asked innocently.
"You know that favour you owe me?"
Xander tensed. "Yes..." he replied warily.
"Dress as Ziggy Stardust for Halloween." Buffy said.
"Not a chance." Xander scoffed.
"You owe me, Xand." Buffy reminded him.
"I know I do, but couldn't you choose something... less mortifying?" Xander whined.
"Not a chance." Buffy said, throwing his own words back at him.
"Fine." said Xander resignedly.
Both Willow and Buffy helped to choose Xander's costume from Ethan's. They couldn't stop laughing while they chose things.
They only laughed harder when they saw Xander in his costume.
Ziggy looked around, bemused. Where was he? Who were all these little goblin things? And why we're looking at him as though he was food? And why we're they running towards him menacingly?
And then Ziggy played guitar.
Entranced, the goblin-children stopped and stared.
Then Ziggy began to sing.
"There's a Starman, waiting in the sky..."
Then there was a flash of light, and Ziggy saw it. The Earth. He could see it through the window of what surely must be a spaceship. He must've been transported whilst singing.
Ziggy could see, emblazoned on the side of the spaceship, the name "Starman".
"Well well" Ziggy mused aloud. "It looks like you really were waiting in the sky."
Then Ziggy saw, in front of him, a great big red button. It would be against Ziggy's nature not to press a great big red button. So he pressed it.
All across the world, children began to boogie.