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Sex is one of those things you have to learn through trial and error.

The only real way most of us get a sense of what sex is like in practice is through films rated PG-13 or higher. While these films provide some information about what to expect, they often fail to capture the messy, uncomfortable, and sometimes dangerous reality of sex.

Luckily, we live in the digital age where people don't mind sharing. And they did so in abundance in a recent Reddit thread asking people to name one sexual act they would never do again.

Shower sex tops the list of failed sex adventures.

Users immediately responded enthusiastically, sharing their own failed sexual adventures. Shower sex topped the list.

It makes for beautiful, cinematic moments, with all that water flowing over tangled bodies. But in reality, it can be uncomfortable. Water not only washes away the natural lubricant, but the steam in the shower can also leave you feeling a little disoriented.

"Having sex in the shower, bent over, made me dizzy, like I was going to faint," one user shared. Nearly 5,000 people liked the comment. Anyone with low blood pressure or who has ever showered without eating can relate to a similar feeling. Apparently, there's a physiological reason for it.

According to Medical News Today, this is because the vagus nerve becomes overstimulated during both sex and a hot shower. This overstimulation leads to a drop in blood pressure, which can make you feel dizzy or even faint.

Outdoor locations were also out of the question.

Another sexual mishap came from someone who'd had it out in the woods. "So many mosquito bites. Like, so many," the Redditor wrote. We're sure those mosquitoes, with all that extra blood pumping through their veins, were having a blast. Dinner and a movie.

The woods aren't the only outdoor location that's caused problems. Someone else shared that they'll never have sex on the beach again. "You forget about the sand, but then you quickly remember the sand," she wrote.

People described the things that were "burning".

For others, it was the aids themselves that caused problems. "My girlfriend gave me oral sex while she had a very strong peppermint in her mouth," another user shared. "It sounds great on paper, but my penis hurt like hell."

There was another incident involving burns, caused by a meal prepared just before the incident. "I had a sort of casual sex relationship with a guy in high school. I was at his house, and he had just made a grilled cheese sandwich. No big deal, right? Well, he hadn't told me he'd made his grilled cheese sandwich with Tabasco sauce. I stuck one finger in and screamed. It took us a while to figure out why I was on fire."

Interestingly, this "friend" married the commenter's best friend. She concluded her story with a thought. "Sometimes I see him putting Tabasco on his food and wonder if that ever happened to her," she wrote.

Spitting was also frowned upon by some.

Other horror stories involved people acting out their sexual fantasies without asking permission. "Once, a guy spit in my mouth without asking, and I almost reflexively punched him right in the nose. Never again."

Sadly, someone could relate to this. "My ex-husband did that to me," another user wrote. "It was so disgusting. He smoked and didn't have good oral hygiene. It was truly traumatic."

To each his own? Try everything once? Honestly, we don't know. A little adventure can be fun, but remember, things can go wrong quickly when it comes to sex.

What's your worst experience that you'll never repeat again? Leave a comment... we're curious.