In the late stages of WWII, Japanese airmen deliberately crashed their planes into enemy targets. These suicidal pilots were called kamikaze – literally, divine wind.
That name came from a force that had saved their ancestors. In the late 13th century, an immense fleet of Mongol ships brought invaders to Japan's shores. When a sudden storm arose and destroyed those ships, the grateful populace called it divine wind.
These days, evoking the WWII meaning, kamikaze usually describes severe disregard for personal welfare.
For instance: "Endlessly repeated passions of self-starvation ... [and] kamikaze recklessness ... are displayed for our delectation on countless celebrity Web sites." (Jessica Winter, Slate.com, Mar. 19, 2007)
