I was getting my wisdom teeth out, and they were numbing me up. No big deal - just the usual poke, poke, poke. But at one point, he poked me with the needle and I could tell that he hit something (I'm assuming a nerve?) because my left eye immediately went lazy. That freaked me out real bad. I was honestly wondering if he severed something and if that would be permanent. Thankfully, I regained control of it fairly quickly (within a matter of minutes).