Once upon a time, I taught sex ed to high schoolers. Not to brag or anything, but I could roll a condom onto a banana in front of a classroom of 15-year-olds and maintain my composure. No big deal.

What I had a harder time maintaining composure about, though, were the egregiously misguided myths about sex that so many teens still harbored. And as it turns out, a lot of these myths are widespread.

Ladies and gentleman, I give you the top five falsehoods about sex that our nation's future believes to be true:

Sometimes, less is more.

Sometimes, less is more.

1. Two condoms are better than one. That seems like it should make sense, because, you know, double the protection, and all. But guess what happens when rubber meets rubber meets friction? Breakage.

And guess what happens with breakage? Spillage. Of sperm. Into vaginas, anuses and mouths, thereby increasing the risk for STDs and pregnancy.

Don't be afraid.

Don't be afraid.

2. Too much masturbation will damage your sexual organs. This is basically the modern-day version of “jerking off will grow hair on your palms.” Teens might be extra likely to believe it because no one is telling them about how masturbation is actually healthy and normal.

But “genitals are meant to have a lot of stimulation,” says Catherine Toyooka, sex educator and founder of Catherine Coaches. “Unless you are using sex toys in a way that is not recommended, like putting a vibrating bullet up your butt, you are not going to do damage.”

Not as scary as they look!

Not as scary as they look!

3. Sex toys can cause STDs. Now, there is some truth to this one. If you're using a sex toy with another person, and you pass it back and forth, and you don't clean it, and that other person has an STD, then yeah, the toy can be a conduit.

Similarly, if you're riding that rabbit by yourself and you have an STD, you could reinfect yourself later on, says sex educator Sandra Daugherty, of the Sex Nerd Sandra podcast.

But if there's no STD to begin with, sex toys alone won't give you one.

Some kids think you can bounce your way out of pregnancy. You can't.

Some kids think you can bounce your way out of pregnancy. You can't.

4. Jumping up and down after sex will keep you from getting pregnant. Gravity, right? We can all get on board with that. (I know some of you grown-ups out there are asking yourselves even as we speak, “Wait, is that really a myth?” It's OK. This is a safe space).

But no — like Las Vegas, what happens in the vagina stays in the vagina. “Sperm can live quite happily in the uterus for up to seven days,” says Toyooka, “so no amount of jumping is going to get that stuff out.”

A delicious drink. Not an effective form of birth control.

A delicious drink. Not an effective form of birth control.

5. Drinking Mountain Dew is a form of contraception. The idea behind this myth is that a dye used in Mountain Dew called Yellow 5 lowers a man's sperm count; fewer sperm, less risk of pregnancy. But this is a falsehood.

“Generally, there's nothing in our foods that's going to stop us from getting pregnant,” said Daugherty. “There would be a lot less pregnancy going on if that were the case.”

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