The slang is referred to it as "Post Nut Clarity". What you're feeling is the rush of temporary neurological sobriety after partaking in the hormonal cravings of PMO. When one first uses a drug it "gives" somebody something in the transaction. When the user is using a drug out of addiction, the effects of the reward center of the brain are no longer "giving" but are rather temporarily "restoring" some sense of self to the user by consuming the drug once more. You're more or less feeling the transition in real time when you leave the trance like experience of masturbating and re-enter the frame of mind that you would normally maintain when not feeling the reward center's anxious demands. The exit is fast and can feel very jolting, considering the immediate recoil you may have at observing what you've been doing for the last twenty minutes or longer.
