The magic words are from the rakugo titled "Shinigami" and are to send death gods back to the underworld. but in the story, at some point, the protagonist saves someone's life by ordering his bed to be turned around (because he should only send death gods back, if they're sitting at the sick person's foot, not at the head).
While it's not rare from Minamoto Hisanari-sensei to have some absolutely crazy references to totally random things, I think there is a connection here, why she chosen this as the magic words. That is, in the rakugo something/someone gets turned around/
reversed, and here, Yuri Fairy's - most likely placebo - magic words "turned" those two characters
reversible, or how to say, so, switches, not stictly top or bottom. (they very likely were switches to begin with though, and this is again just placebo XD)
It can be I'm assuming wrongly and it's just a random reference, but I think I see a connection here. Kind of interesting, I think. XD
If anyone is interested in the rakugo itself, (and if it could help understanding the TL note) here's a youtube link.
https://www.youtube.com/watch?v=RZWNNZIps0s