I was laying around twitching a few minutes ago when I came to the conclusion that, whenever you twitch, that is you in another universe being hurt immensely there. Like, say your leg twitches. In another universe at that same moment you some how broke it, or something happened to that spot on your leg.
It is like when you are trying to convince yourself to do something. You struggle with yourself, but manage to work up the courage to do it, and then at the very last second puss out and you get that big rush over your body like 'Oh my god, I cannot believe I just almost did that'. That is a weaker, and less precise feeling you get. A twitch is the stronger, more accurate end of the spectrum. In another universe, you managed to do what you decided not to, and in another universe your twitch was a broken bone.