http://en.wikipedia.org/wiki/The_little_death
The little death is a translation from the French "la petite mort," a popular reference for a sexual orgasm. The term has generally been interpreted to describe the post-orgasmic fainting spells[1] some lovers experience. Also, it can refer to the spiritual release that comes with orgasm, or a short period of melancholy or transcendence, as a result of the expenditure or spending of "life force".