Place this clip right after the reveal in a fail montage, then follow it with the SpongeBob Sad Song for a second, smaller letdown later in the same edit. Keep it for the main flop and reserve the paired sound for the callback gag at the end.
About this sound
This 12-second clip is Fat Tony performing a slow violin piece on Sophie's instrument in The Simpsons. The stretched, plaintive notes deliver theatrical sorrow that turns disappointment and defeat into dry, mock-serious comedy. It comes from 'Insane Clown Poppy,' the season 12 episode first broadcast in 2000, where Krusty reconnects with his daughter.