WHAT TRIGGERS YOUR ORGASM when you MASTURBATE

Just curious, What triggers you in that EXACT moment, when you're Masturbating, when you are stroking your Cock or your Pussy/Clit, when suddenly you KNOW you have crossed that Line and you KNOW a fantastic Orgasm is just about to happen?  For me -- usually watching Adult Videos -- it's somewhere around when that huge Cock goes into her hungry mouth just a bit more as she moans in pleasure, or maybe that moment when a huge Cock thrusts into her Pussy just a bit deeper as she wails in pleasure, or maybe as that Cumshot arcs over her face in slow motion and most of it lands on her face, maybe as the camera is focused straight up between those 2 hot Ass Cheeks... Hard to say, but there is that MOMENT, as I'm stroking my lubed Cock, when Anticipation become Confirmation and I know I'm about to blast CUM all over the place as I stroke faster and faster...  How about you?