Jimmy slashed Quaunt with the sword is a copypasta that was used by Dio and Hipper mostly.
This meme originated on January 14th, 2017. In chat, a user known as Jimmy1999 (who was already a meme thanks to his grammar, outrages statements, and hatred of Robbie Rotten) stated "Jimmy slashed Quaunt with the sword." Jimmy probably said this because he was mad at Quaunt. It became a copypasta in record time. It was probably because of the poor grammar mixed with the attempt to use /me. Jimmy did not approve of this.