Basically any of the "you can't get pregnant if" myths. Probably the dumbest one I've ever heard is that standing up and opening your legs after sex will prevent you from getting pregnant. Seriously, who came up with that bright idea?
You can get pregnant from anal. (that was when I was in high school of course).
Really? That was told at your HS? Back when I was in HS it was common knowledge that doing anal was how to avoid pregnancy and keep the girl's virginity intact. So of course that's what my HS GF and I first engaged in.
We did hear that if a girl douches with Pepsi Cola after it would prevent pregnancy...
Another wacky one is that if a man gets pegged by his GF or Spouse, it will turn him gay.
I have heard the one about pegging before. Also once heard that any guy who wishes to engage in anal sex (mind you this was on the giving end of it) was secretly gay.
Other myths I heard, that STD's/STI's can't be transmitted during oral and anal sex. That if the man masturbates before sex he won't get the girl pregnant because all the sperm will be "washed" out of his system.
Was taught by my high school principal that the pill was made from horse urine. (I'm sure this was to deter us from using any contraception.)
No, that's Premarin, and that's used mostly in post-menopausal women for hormone replacement therapy. I don't think CEE (conjugated equine estrogen) is commonly used in birth control pills these days, though it may have been once.
Luckily I was pretty knowledgeable about sex from an early age, but I do remember hearing about douching with cola and BLEACH (oh GOD) will prevent pregnancy. If the girl is on top she can't get pregnant, if she's on her period she can't get pregnant...
I think my favorite "myth" of all is just straight up anatomical ignorance. I heard a guy saying he was going to "put his finger in" a girl's clitoris. You realize that's not a hole... right??? I'm pretty sure he meant in her vagina (he maybe thought the vaginal opening was called the clit) because wtf, the clit is most definitely NOT a hole.