0 energy level may represents the original level before u have either sex or chocolate i.e. it is relative level. Once u start to have sex...energy level raises from 0 to 250...its practically true...unknown source of enery.... then graph..is ok upto final point (nails already explained)..... but graph again should be modifieda bit......when u finished sex....you have got -ve energy relative to the reference level....its practically true I dont think chocolate povides energy in exponential nature.