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Dancing Rat Jumpscare
Dancing Rat Jumpscare is a Discord originated screamer that was posted by the user Sargentcrackhead on both their account and their YouTube channel in August 2020.
Video
For the first three seconds, we see a clip from a 2001 3D animation by Michael Loeck of a mouse dancing to "You Sexy Thing" by Hot Chocolate. Just after the mouse turns around, a man's screaming face with a blood red complexion pops up with a loud droning scream.
Link
NOTE: The first link contains a screamer.
youtube.com/watch?v=HiOhUAp6MT8
youtube.com/watch?v=6gb73wi3OEg - Original video with no screamer