Well, it's kinda a double problem...
if you tell people, "You shouldn't kill me, I'll explode and kill you too!" they'll just kill you from far away.
if you don't tell them, you are probibly going to be more likely to just blow up your friends who are trying to get your flatlining self to an Evac point so docwagon can patch you back together.
you could do it to someone else as a threat, a cranial nuke or kink-bomb of some sort. (that's classic enough to happen ocasionally) but it's so expencive, that it's often not worth the effort.
A better 'death knell' would be to have a wireless transmitter, broadcasting the last ten minutes of video to the matrix in a public forum, letting everyone know who killed you.
then, thoes who know you; know where to go to get revenge.
-RuskiFace the Pirate