Idk if this is something exclusive to the NBA fandom but within the NBA there's the expression "your favorite player's favorite player". It's not meant literally, it just means a player who is highly respected even by other NBA players. In the NBA, I'd say Kobe Bryant is an example of this, highly respected by both his peers and younger players.
Who do you think this is in the kpop/idol world? Answering the literal meaning of the question is also acceptable if you happen to know or if you just read the title 
