The character of Vincent van Ghoul, voiced by Vincent Price" first appeared in The 13 Ghosts of Scooby-Doo (1985) as a warlock who helped the Scooby gang capture 13 escaped ghosts. In this incarnation Vincent van Ghoul is a horror actor, now voiced by Maurice LaMarche, and some of Vincent Price's classic roles are referenced in "NightFright" such as The Fly (1958) and The Abominable Dr. Phibes (1971).
The repeated statements about "needing to tinkle" are likely references to Price's film, The Tingler (1959), consistent with other reminders of his career in this episode.
Shaggy and Scooby win a contest to have dinner with Vincent Van Ghoul, a character inspired by the legendary actor Vincent Price, who voiced the character in a number of appearances until his death in 1993. In addition to acting Vincent Price was a gourmet chef who wrote several cookbooks and was known to throw elaborate dinner parties for his friends.