Pyschological term for "the straw that broke the camel's back".
When a human is faced with too many stressors, or is in an ongoing, negative, unhealthy pyschological situaion, one event may be enough to push them over the edge, and take drastic measures. The actual event may be misconstrued as the "cause" of the drastic behaviour, when in fact it was just the last thing they could take before breaking.