Y’know how Yurio calls Yuuri “Katsudon”? It kind of sounds like his last name, “Katsuki”, and it’s his favorite food too, so I think it’s a fitting nickname.
What if Yuuri starts calling Yurio “Pirozhki”? It’s similar-sounding to his last name “Plisetsky” (well… they both start with “p” and end with a “ki/ky” at least lol) and it’s his favorite food too.