To cum onto a woman's stomach, unannounced. The origin stems from the fact that this act has an element of shock and surprise, but is not truly frightening. This twist at the end, gives its it whole new spin, much like one of Shyamalan's movies.
So I was with Dustin the other night, then bam, plot twist, I was M. Night Shyamalaned.
I had to grab a hand towel from the bathroom after that M. Night Shyamalan.