Place this clip at the exact reveal in your edit, just before a reaction beat. Follow it with the scream meme sound button for panic, or lead into it with the oh my god meme sound button when the character realises first.
Über diesen Sound
This is a short 3.4 second spoken line delivering the phrase we live in actual nightmare in a flat, unsettled voice. It feels quietly horrifying rather than loud, turning a cheerful setup into dread in an instant. It comes from Don't Hug Me I'm Scared, the puppet series known for sweet lessons that slide into surreal horror.