I'd take the (insert tool of death here) away from 你 and hold 你 until it ended; coaxing 你 and trying to calm 你 down. And if that doesn't work; try and knock some sense into 你 (without hitting 你 physically)
I'd say 你 are being an attention whore and if 你 was going to do it 你 would have done it sooner. 或者 I would probably (If I believed you) tell 你 not to do it.
I'd tell 你 that everyone has tried but that I know 你 won't go through with it because your asking us to stop 你 which means 你 won't do it. So honestly I'd tell 你 to go ahead and do it.
If 你 were hanging yourself; I'd ask 你 if 你 had any spare rope 或者 cloth 或者 whatever you'd use.
If 你 were taking some pills; I'd ask for whatever's left.
If 你 were cutting your wrists; I'd ask if I could use it after you.
If 你 jumped off a cliff; I'd run over yelling at 你 to stop, then when I catch up to 你 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 你 were to 移动 in front of a moving car; I'd stand there right behind 你 (stronger impact 由 being moved 由 two exceedingly, extremely fast and furious massive (NO offense, not callin' 你 fat 或者 anything) objects...
If 你 were to drink posion; Ask 或者 just take whatever's left (I mean, you'd be dead anywyas...it wouldn't really bother 你 if I took the remainders of whatever 你 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!