This video is antiquated! (Old and Crap) Here's the new video!
https://www.youtube.com/watch?v=ibDu0dCeUE8
This is a short tutorial on getting a simple button toggle working using Udon, the new VRChat scripting system. As an example, we're using it to toggle a mirror on and off. I've also included a segment on doing the same thing in UdonSharp, the C# compiler by Merlin allowing for actual coding for VRChat.
VRChat Udon SDK:
https://vrchat.com/home/download
UdonSharp:
https://github.com/Merlin-san/UdonSharp