No, it does not exist. It takes a lot more than just a pinch to knock someone out.
Once again, we can thank television for this false idea. Don't believe everything you watch on TV (or in the movies or in books for that matter).
Pressure points usually need to be striked with a reasonable amount of force and it's relatively unlikely, even then, to result in KO. Pressure points can, however, hurt incredibly and cause numbing, but require great precision and expertise to use with any real chance of being effective (this means you've got to be a reasonably expert striker/grappler already to use them anyway).
Edited by Leo_E_49 (08/22/05 12:31 PM)
(Website by Marc MacYoung, not me)