Dear suicidal residents of /corky/,
The most peaceful, guaranteed way to kill yourself is helium or nitrogen in a clear plastic bag taped over your head.
The reason asphyxiation is normally traumatic is that your lungs detect build-up of carbon dioxide, and then your body freaks out sending pain signals all over the place. Helium or nitrogen fools this mechanism. You have about 5 minutes of light-headedness, like drunkeness without nausea, followed by 10-15 mins of unconciousness and then brain death.
Helium is obtainable all over the place, as are duct-tape and clear plastic bags. Your hearing is the sense that shuts down last, so load up an mp3 player with about 20mins of triumphant exit tunes, and gently drift off into the ether.
So... now you know the most efficient, painless, guaranteed way of physical exit, what you need to understand is that psychologically you should never kill yourself when you are actually feeling suicidal.
Survivor statistics indicate that at the moment of unconciousness many, many sucicidal people become acutely aware that this wasn't actually what they wanted after all.
What they wanted was options, and being dead simply doesn't provide the opportunity for options. Believe it or not, there are many people who can help you find these options, even in your current circumstances. All you have to do is actively look for them.