A stranger is about to jump off a bridge right in front of you. You don’t know his troubles, or why he’s been driven to do this, but you have one chance to yell out something to persuade him that life is worth living.
What do you say?
“Help! Help! Please can you help me!”. It might just take their mind off their own problems to come to your aid.
Before you jump, may I have all the money in your wallet?
It’s either a great idea, or a brilliant reference to the scene from Spider Robinson’s Mindkiller. Either way, my hat’s off to you, sir.
"My girlfriend told me to bring another guy over for her oversexed roomie. Want come?"
I think this webcomic says it all. Note-not work safe.
No! Don’t jump! Because it would seriously traumatise me to witness you hurling yourself off this bridge, and I’d probably have to be in therapy for the rest of my life. I think you can appreciate that however bad things are for you at the moment, it would be pretty terrible if your last act was to sentence me to a lifetime of mental anguish. I’d wake up in the middle of the night wondering if there was anything I could possibly have said that would have had made you change your mind, and make you realise that life is worth living. I’d be tormented by guilt and regret, and probably wreck my life as well, because of my inability to come to terms with the shock of witnessing such a tragedy…
…
*SPLASH *
“Make sure you get it right the first time,
cause Nothing’s worse, than a SUICIDE CHUMP”
F. Zappa
“Hey! Buddy! Your shoelaces are untied…”
Go ahead and jump. After you hit the water I’m gonna find your wife and bang the shit out of her.
That might piss him off enough to come down and try to kick my ass. Then, I’d grab him and prevent him from jumping.
Months later, I’d find his wife and bang the shit out of her!!! 
I wouldn’t say a word. To live or die is his (or her) decision to make, not mine.
"Oh, you think you’re going to jump off there? Yeah, right! I know a coward when I see one… and I’m seeing one right now! In fact, I’ll bet you a hundred bucks that you don’t jump! What do you say, chicken-boy? (makes chicken noises)
What are you waiting for? You think all your problems are going to solve themselves while you stand there? Get on with it! I have better things to do than stand here waiting for some weak-willed loser to realize that he won’t jump off a bridge, climb down, get back in his car, and drive home to cry himself to sleep!
nothing. no one made you god, his life is still his choice. I always hate to wake up getting my stomach pumped out because some moron decided to be mr. good semeratin pluse being shoved in the mental hospital afterwards sucks