The reason why Dani Ceballos was insulted ("Die, Ceballos") in Getafe during LaLiga match

Dani Ceballos, Real Madrid midfielder, was booed at Getafe last night, during a 1-0 victory for Real Madrid, important for the team in LaLiga (four points behind Barcelona). Some spectators at the Coliseum stadium shouted "Die, Ceballos!" when the midfielder, who has been side-lined for weeks due to an injury, substituted Arda Güler (who scored the only goal) in the 77th minute.

Referee heard the insults, and activated the "anti-hate protocol": through the loudspeakers, it was warned that the match would be suspended if more insults happened again. The match was halted for one minute, but resumed with no further incidents.

Why do Getafe, a city south of Madrid, hate Ceballos? It dates back to 2016, when the midfielder played in Betis, in the final match of the season. Betis defeated Getafe, and Getafe was relegated to second division. And, apparently, Ceballos said "I hope you rot in the Second Division and disappear" to Getafe player Juan Cala. The team got promoted back to first division the following year, and has remained there ever since.