Well actually there is.
Suicidals are dead.
Those who claim they will, however, are faking it, otherwise they wouldn't be saying they are, let alone repeatedly.
Of the few I've personally known or ever heard of that committed suicide, not a single person saw it coming. Sure, in retrospect there may have been 'signs,' but basically it was unexpected. Also such signs can be witnessed in many others who haven't, so that's just a hindsight 20/20 thing.
Of they numerous I've witnessed that claim to be suicidal, I've yet to hear of one who has, despite their flag waving announcements.
Before this site, I use to be active on a forum where suicide announcements were common. Many came to me for advice, even cajoling and trying to force me to listen to their problemz despite me telling them it depressed me. I must have been good at it, because not a single one of those killed themselves.
The only one on that site I knew that did was a total shock, as he had not so much as given a hint, not even to his gf, who posted it after. The dude was in his 30s, brilliant, super witty, and a joy to interact with - his forays onto the forum being a rare treat I looked forward to. Truly sad, and a total waste.