I'm not a suicidal man by nature. Except when I am. Which is never. Well, that's OK, then.
Mind you, were I suicidal, which I'm not, I can think of a worse way to go than dying than via a caffeine overdose. Actually, I can think of loads of worse ways of dying; some of them could be self-inflicted. Not that I'm planning anything. Oh, no.
Anyway, where was I? Suicide. That's it. ODs on caffeine. The practical guide. Here.
If you're wondering what a caffeine overdose is actually like, then take a look here. It's pretty comprehensive, but I would dispute the order of symptoms towards the end...