I would imagine that Equestria's version of the Cone of Silence as a bunch of magically enhanced gemstones that have the same effect like the original. However, it turns out that it was created by Princess Luna as a joke, and nopony figured it out for centuries until she was purified by the Elements of Harmony. She couldn't stop laughing when she found out that her prank was being used in a serious way.



Celestia, meanwhile would secretly send the director of Equestria's spy agency ridiculous names to call himself every day "for reasons of security", such as "Flobber Wobber Bobber Bobber Bobber Bobber"! Unlike the Cone of Silence, it would stay a secret between the Princesses. (Can you guess the reference?)