If I had to take a stab at it, I'd say the anticipation then full on rush of the scariest roller coaster at its zenith, then onslaught, combined with the "good scare" you get at the most intense part of your favorite horror movie, mixed with the excitement then happiness of getting EXACTLY what you wanted for that perfect Christmas, intertwined with the pleasure that comes from your favorite sweets when they are fresh from an oven, enhanced by the contentedness of lying in that perfect person's arms, and left with the euphoric high that lingers in your and body after you were just kissed like you are when you are "reaaallly" kissed.......
Nope, no idea. 😉