I'm sure there are loads of reasons, and no doubt ultimately everything we do is determined by a combination of body chemistry and social control, but still, suicide makes a lot of sense - if you just keep hanging on you're bound to end badly, in the end. Most people do, and it ranges from mildly unpleasant to horrifically painful.
Wait, you're not ready to give up the good food and good Thai putana yet, are you, opebo?
No, not yet, but let us not forget, Grumps, that all our sensory organs, as well as the desirables they delect, will very soon be worm-food. I certainly wouldn't be averse to a good old injection a bit before the bitter end, or perhaps strapped up with the proper equipment among someone against whom I bear a grudge. Remember, our brevity of existence has the potential to be a weapon of sorts, n'est-ce pas?
