Post-Orgasm Clarity (POC), to be a little more specific. The worst part of sex is the post-orgasm clarity. That is, if you're still having promiscuous (hopefully protected) sex with different partners. In a loving, caring relationship, post-orgasm clarity is just wonderful. You get some things off your chest, (or on your chest, on a fun night... winky-face) you reconfirm your commitment and dedication to one another while enjoying the freedom of such an intimate moment with someone you can trust.
On the other hand, outside of a loving relationship, post-orgasm clarity (POC) is the worst thing that could possibly happen to a human. Ever. For women, it's usually not as devastating, because with the multiple orgasm set-up, one orgasm just drives you on into chasing the next and therefore gives you a slower downslope into self-loathing. In a man, however, the moment after an orgasm is like driving a car 50 miles an hour into the wall of an elementary school, that's made up entirely of harsh realizations, regret and now-obvious truths. The first thing I thought after losing my virginity was, "Wow. This really could have waited. And.... I don't ever want to see this person again." I didn't want to feel like that. But that's what happens when male genitalia release their strangle-hold on the male brain, and all senses come back into full function.
A penis is kind of like the guy who convinces you to buy tickets to go to Vegas, loan him some money, and then tells you to keep gambling the money you have even though you're losing all of it, including your plane ticket home, and walks up to you afterwards and says, "Wow, man. Those were some terrible bets. I hope you find a way back home." And he proceeds to get on the plane alone, with his un-bet ticket, having not spent any of the money you gave him. That is what it's like, ladies, when a guy is horny. The penis has this strange "override" password to the brain that it's irresponsibly willing to use at the drop of a hat (or the drop of a pair of panties), that can completely alter all five senses and any sense of right and wrong. (Look it up, it's science, yo.) But then, in the moments when everything makes so much sense and life is perfect and you know that every little thing you've done to place you at this moment shouldn't just be done the same, but with a sense of pride, knowing it was the right step all along because you ended up right, here... in those moments, the Penis (AKA Dick) is packing his bags to skip town before his little ponzie scheme catches up to him.
Then the POC comes crashing down on you, mercilessly. Shamelessly. "You don't belong with this girl." or "You started without a condom." or "You finished without a condom." or "We both knew you weren't going to be able to pull out." or "You shouldn't have put your mouth there." or "You shouldn't have let her put her finger in there." or "You made eye-contact with the cat the whole time."
In it rushes. All at once. Suddenly, you know the right answer to everything that's happening in your life. You know who you're going to vote for, what you need to do to get in shape, the meaning of life, and why and how you will never go to a bar and have a one-night stand again. "Dick" has released all of the blood-flow back to your brain and you're now allowed to do as you please.
This reason is the reason that masturbation is such an important part of life. It offers a minor, shorter form of POC, while avoiding most (not all) feelings of shame and self-loathing. Suddenly, you know that you don't want to be with your best friend's super-hot ex-girlfriend. Suddenly, you don't want to have sex with your ex. Suddenly you're too sleepy to get up and finish that cold, three day old pizza.
