Recently there was a post on MO containing: "If I can't figure this out I am going to KILL MYSELF!! (not really)". Although the parenthesis suggest that it is probably not meant seriously, still maybe some places where related issues have been discussed are worth mentioning.

Meta Stack Exchange: What's the official SE response to serious mentions of suicide or self-harm in posts? and Mathematics Meta: Understanding the community stand point on posts about self harming