Fugu Poisoning.
It's called Tetrodotoxin.
When you consume it, it will block the receptors in Neuromuscular junction receptors causing uncontrollable muscle contraction. You get the thing called "Locked Jaw" basically you die due to muscle contraction all over your body..
I think it only takes you 25 milligrams and at least 17 minutes to kill you...
I have many more ideas... just don't know how to make it.
I mean why not make a wrist band- kind of machine that works like a wallet, cell phone, note pad, calendar, etc... make life way easier that way.