As mentioned in the movie, it is forbidden for Wong to teach ping pong to "gwai lo". This is most likely a reference to Dragon: The Bruce Lee Story (1993) starring Jason Scott Lee. Bruce was forbidden by the elders to teach martial arts to anyone other than Asians. Jason Scott Lee appears in "Balls of Fury" as Siu-Foo.
Jason Scott Lee tells the Ping Pong master he cannot teach gwei-loh, or foreigners. Jason Scott Lee played Bruce Lee in Dragon, a biopic about Bruce Lee. In that movie, Dragon, Jason Scott Lee (as Bruce Lee) was teaching Kung Fu to foreigners and he was summoned to a council to fight as punishment for his transgressions. Jason Scott Lee then warns the Ping Pong master he would have to face the Dragon if he continues to teach foreigners, most likely a reference to his own movie.