It’s a pony parody. Of Bounce by System of a Down. No further explanation required.

 

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Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony! Pony!