Sesame Street/Nightmare Fuel

During the "Monster in the Mirror" song, when Grover is walking alongside a street, there's a crudley animated reflection of him in the mirror. When he says "Told the monster in the mirror, no, I am not scared" the reflection takes on a scary appearence that more resembles Pennywise the clown impersonating Grover. and it goes by in 3 seconds. At 0:57 http://www.youtube.com/watch?v=wNMwRH5UGYY.

The classic example: Ernie and Bert in the pyramid, and the statue coming to life only when Ernie's alone.