It doesn't work, actually. Your body won't allow you to hold your breath long enough to die. It won't even let you do it long enough to fall unconscious, in most cases (and if you happen to be one of the exceptions, you just start breathing normally again once you fall unconscious anyway).
(Edited 29 seconds later.)
@OP
Sorry, I passed out and started breathing again.
Obviously, this whole post is some elaborate trolling targeted at people wanting to commit suicide. You should be ashamed of yourself, OP, for giving these people false hopes.
EDIT: Also, you forgot your pony picture.
(Edited 4 minutes later.)