I've experienced the shivers and twitching and uncontrolled movement.
Shivers I normally get from my first hit off a real nice spliff. My whole body get engaulphed by a wave of it.
Twitching I get sometimes, not all the time, my eye will do it, arms, legs, most of the time its my hands though.
Uncontrolled movement I used to get when I first started, but it has stopped. I used to put my hands in my pockets, and they would move non-stop. I could not stop them from moving. I am dead serious. I looked like a fuckin retard everytime I reached in my pocket for something cuz u'd just see my hand moving like CRAZY in there. You know how hard it is to grab something in there where u can't keep ur hand still? Sometimes id have to use my other hand to kinda flatten it against my thight then slide my fingers down till i grasped what I needed.