I'd take the (insert tool of death here) away from tu and hold tu until it ended; coaxing tu and trying to calm tu down. And if that doesn't work; try and knock some sense into tu (without hitting tu physically)
I'd say tu are being an attention whore and if tu was going to do it tu would have done it sooner. o I would probably (If I believed you) tell tu not to do it.
I'd tell tu that everyone has tried but that I know tu won't go through with it because your asking us to stop tu which means tu won't do it. So honestly I'd tell tu to go ahead and do it.
If tu were hanging yourself; I'd ask tu if tu had any spare rope o cloth o whatever you'd use.
If tu were taking some pills; I'd ask for whatever's left.
If tu were cutting your wrists; I'd ask if I could use it after you.
If tu jumped off a cliff; I'd run over yelling at tu to stop, then when I catch up to tu before its to late I'll suggest that we jump off together. :) It'll add to the adrenaline rush before our untimely yet at the same time timely deaths. ^_^
If tu were to mover in front of a moving car; I'd stand there right behind tu (stronger impact por being moved por two exceedingly, extremely fast and furious massive (NO offense, not callin' tu fat o anything) objects...
If tu were to drink posion; Ask o just take whatever's left (I mean, you'd be dead anywyas...it wouldn't really bother tu if I took the remainders of whatever tu used when you're dead, wouldn't it? =/)
Scream, 'STOP!' No ONE has the right to do suicide. Trust me, I've tried it plenty of times... not fun, at all. It's a serious matter and I wish people in places such as the media would understand just how tortured it can make people. Just NEVER poke fun of something like that with me, because it's not funny in the least!