Panels from the Porky Pig story in Looney Tunes and Merrie Melodies Comics (1941 series) #2 (November 1941), pencils and inks by Roger Armstrong (?)
Oh course, where Porky's a celebrity at a celebrity restaurant, you have other celebrities rubbing his pork shoulders! First panel: James Cagney, Groucho and Harpo Marx! Second panel: Dorothy Lamour! Fourth panel! Jimmy Stewart!
But, at least as far as the Warner Bros. cartoon department is concerned, the biggest celebrity cameo appearance is by Leon Schlesinger, producer of the Looney Tunes and Merrie Melodies cartoons, therefore making him Porky's boss! In a relationship that will surprise no one, Schlesinger was also nepotistically related to the actual Warner Bros. As Raul Julia would sing: "Harry, Sammy, Irving, and Jack!"
Here's an actual, I mean real-life, son, appearance by Leon Schlesinger in the May 1940 Looney Tunes short "You Ought to Be in Pictures." The timing of this followed by the comic book about a year later tells me the cartoon likely inspired Leon's appearance in this comic story.
Looney Tunes "You Ought to Be in Pictures" (1940), story by Jack Miller, voices by Mel Blanc, music by Carl W. Stalling, produced by Leon Schlesinger, directed by Friz Freleng
Leon Schlesinger is also boss of Warners' stars Bugs Bunny and Elmer Fudd. And probably even that %!#@^ing Buddy.
Later, Elmer tries to convince Leon that Porky should go west, and Schlesinger thinks he means "rest," and oh boy, hilarity ensues.