I'm Dr.

Lindsey Doe, clinical sexologist and host of this sex curious show Sexplanations. This video about four surprising sex experiences I've had is sponsored by AdamandEve.com. [WHIP CRACKING, COUGH].

Back in the 1960s, researchers William Masters and Virginia Johnson observed people having sex and masturbating in their laboratory. They collected data on 10,000 episodes of arousal and plotted the trends on a graph as four stages. Excitement, in which heart rates, breathing, and blood pressure increases.

Nipples get erect, muscles tone up, the genitals fill up with blood. Labia get bigger, flatten out and spread apart. The vagina gets wet and starts to change shape called tenting.

Penises become erect and the scrotum holding testicles thickens. And for most of us there's a reddish rash looking thing on the chest called a sex flush. Plateau is the second stage, time is still passing but the level of arousal doesn't change much.

The vaginal walls do tighten, creating an orgasmic platform in the first third of the vagina that can grip anything inserted. The testicles raise up and enlarge by 50%, and sometimes a clear droplet of fluid comes out the urethra of the penis called pre-cum. Then stage three is an orgasm or more than one orgasm.

And in stage four, called Resolution, the body returns to homeostasis. For some of you these changes might be sex surprises in themselves but I know this pattern. For me it's pretty consistent.

Get turned on, find a groove, lose myself, calm back down. One of the earliest surprises to my sexual script was crying after orgasm. We're not taught this in school.

MTV didn't tell about us. There aren't love songs -- “when I do shorty she cries, she cries.” But it is a thing, you can look it up as post-coital tristesse or post-coital distress. Post meaning after, coital meaning sex, tristesse meaning sadness.

There isn't a lot of conclusive information about this surprising reaction to pleasure but there are some solid ideas:. One is that oxytocins released during orgasm to help with pair bonding work. We bond hard and end up worrying more about losing the other person or getting hurt.

Another idea to explain the tears is that sex intensifies the emotions we have already. So if we start having sex kind of down, we'll feel even more down as the sex alters us physiologically. There are variations of this, like instead of being sad, someone get really aloof after sex.

They have sex with a partner and want nothing to do with that person afterward. I would cry but it wasn't because I was sad. I was really happy, in awe of the experience.

Surprise! Everybody's different including their reactions to sex. A more recent surprise was tiny red dots around my eyes, on my cheeks, and under my chin.

FROM SEX! Occasionally I will have such a strong orgasm I just burst blood vessels in my face. This is caused by the pressing down on my diaphragm and holding my breath while coming.

An article in the medical journal, BMJ, sites a similar case of an emergency clinic patient who lost his vision from passionate sex. “During orgasm the valsalva manoeuvre [the thing I do] can produce a sudden increase in retinal venous pressure resulting in vessel rupture and hemorrhagic retinopathy.” Surprise! Sex and masturbation can cover you in spots and make you temporarily blind. Sex and masturbation can also lead to myotonia!

Surprise number three. Myotonia is the “inability to relax voluntary muscle after vigorous effort.” So after sex I wasn't able to move my arms right away and my face stayed in a goofy smile position for nearly five minutes. I could talk through my teeth but I couldn't adjust my cheeks or lips at all.

In fact, the reason I have this picture to show you is because I had no idea what position my face was in and my partner took a photo to show me that of all the ways it could've gotten stuck -- smiling was the one. A fourth sexual surprise I experienced was a major fluid surge out of my body. I know there's still a debate about whether or not “female ejaculate” is urine.

It doesn't matter to me if it is; squirting is exhilarating and I'm confident it isn't because it doesn't smell like, look like, or feel the way it feels to expel urine. Either way, I urinated before sex to empty my bladder -- less competition for space in my body if sex involves penetration. Then I had sex, and enough fluid to fill one pint glass whooshed out of me.

Here's a photo of me in astonishment of my body. A few minutes after this was taken, I got out of bed as usual and went to pee because it's good practice to flush pathogens out of the urethra that may cause infection. There was a half bladder's worth.

It surprised me. Where did all that fluid on the sheets come from? There's a lot about sexuality that is mysterious, elusive, and fascinating.

I kind of love this because it gives me an opportunity to learn. Surprises to my own sexuality are one of the reasons I look into what's going on. It's why I stay curious.

I'd love to hear in the comments what has surprised you about sex? What have you learned from your own experiences? What are you still trying to figure out?

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Surprise yourself!