Here you have a fine example of the scope of Little Death.

A few moments ago, Li'l D announced his imminent action to Big D, which in the common sense would imply some sort of sexual arousal.
But no, it was not the joy of reunion of Mercedes with her boyfriend. In this case, it meant the shock that befell poor Death when he learned that Mercedes had a boyfriend. Just take a peek at the poor guy's petrified look and you'll see what I mean.

As I said: A Little Death can also stand for a sudden negative experience.