What if... What if baby Kakashi accidentally acquired a favorite song?
Like... A pop song? The kind that gets stuck in your head and makes you want to dance? Like, maybe he got a little portable radio for his birthday? (very good gift since a radio can be used for keeping up to date with news and maybe even intercept coded enemy messages on a lucky day?) But then, one day he accidentally tunes in to a music station and gets exposed to whatever dance hit is at the top of the charts that day in the land of Fire, and that dance hit is immediately imprinted to the very core of Kakashi's little joy-deprived soul, awakening urges he never even knew ninjas could have, like: Humming? Foot tapping? Twirling?
Kakashi manages to discreetly obtain a recording of the cursed track and it's like a dirty secret now. Nobody can ever know. Ever! but whenever he's got some time alone he plays it. he plays his song. on repeat. and. he has to dance!
There is choreography to go along with the song, because all good pop hits have choreography and Kakashi discreetly obtains the means to copy and memorize the whole routine (the lead singer is really cute too but that's completely irrelevant is what Kakashi tells himself)
It turns out Kakashi is really good at picking up dance choreography because of course he is. He practices the steps to perfection in the safety of his home. Not even his ninken gets to see. They'd think he'd caught some kind of fever and they wouldn't be completely wrong. The obsession is very intense and makes him act completely out of character and it's all kinds of upsetting. Kakashi never intended for things to go so far and he's not sure how to turn back.
Then the nightmares start...