The 500th Episode Celebration couch gag is the sixth couch gag of Season 23.
The Simpson family runs in the living room as usual, but they see Moe, who's partying and celebrating the milestone of The Simpsons reaching 500 episodes as he says, "Happy 500th episode!" and he blows a party horn. Many other characters enter the room as balloons and confetti fall down, while The Larry Davis Experience plays "Auld Lang Syne". Lisa, being skeptical about this, reads the episode guide and discovers that it's only episode 499, sadly putting an end to the party. Moe replies, "Ah, jeez. Well, I got news for ya. FOX ain't doing this again." and the others moan in disappointment.