A dozen things you never knew about sex ...but probably should

Sex is one of the great enduring mysteries of humankind: everybody loves it, but few of us understand very much about it or how it works. Below, then, are some of the great myths about sex, as well as a fair amount of information you should probably have at your command before you next hop in the sack.

Myth #1: Big hands means he's big…elsewhere.

Hand size has no correlation whatsoever to the size of a man's package, according to AOL health. The results of a study of 104 men with foot sizes eight through 13 surveyed by St. Mary's Hospital and University College Hospital in London found no link between foot size and penis thickness or length, once again proving there is no medical evidence to support this myth.

Myth #2: You can't really tell just by looking (above the waist) if a guy is aroused.

One obvious sign of arousal is found in the nostrils. This is because the inner nose is greatly linked to changes in body temperature. As explained through AOL Health, the nostrils will actually swell very slightly during arousal. Flared nostrils will also tell you when someone is physically attracted to you. The nose, it seems is as telling as the penis.

Myth #3: Bikes won't damage your libido.

Men who frequently ride a bike are at risk of losing some of their sex drive. The seat, a Massachusetts Male Aging Study, explained, puts pressure on the area between the genitals and anus and can damage nerves and cause erectile dysfunction. Bike lovers should invest in padded seats and raise their handlebars to avoid permanent damage.

Myth #4: Regular sexual activity burns just as many calories as a workout at the gym.

Unfortunately, this could not be less true. While it is believed that a healthy sexual appetite can replace a hard gym sesh, the average roll in the sack (30 minutes) only burns about 85 calories, according to AOL Health. With this knowledge, it would take four straight hours of sex to burn off one piece of plain cheese pizza.

Myth #5: Men have significantly more partners during their lives than women.

While it is believed that men, who have a greater sex drive, have far more sexual partners than women, a recent article written on MSNBc said the median number for men is seven. Women, however, are close behind with an average of four. Even more surprising, the study found that 29 percent of American men reported having sex with 15 or more females. Nine percent of women also slept their way past the sexual marker.

Myth #6: A man should last at least a half hour.

While some women hold that a man should be able to last at least 30 minutes during sex (that is, actual sex, not foreplay), but the truth is that the average man is done between five and seven minutes after the thrusting begins. Esquire magazine suggests that thinking about things completely unrelated to sex, as well as some, ahem, non-sex practice (read: your hand) can help guys increase their stamina.

Myth #7: If she's not having an orgasm during sex, he's doing something wrong.

Unfortunately, for women, only a small percentage experience orgasms on a normal basis. According to the Society of Obstetricians and Gynaecologists of Canada, only a third of women reach orgasm during intercourse and many must reach this level of utmost satisfaction through other means. This typically has nothing to do with male's ability in the sack and it is the woman's responsibility to communicate with her partner about her likes and dislikes both during foreplay and sex.

Myth #8: Vaseline works fine as a sexual lubricant.

Vaseline, unlike previously believed, destroys latex by creating small pinholes in the condom, explained AOL health. It is its oil-based nature that makes it a big no-no during bedroom foreplay. Other products to avoid include baby oil and hand lotion. Instead, purchase KY jelly or warming KY and enjoy a night in the sack that won't find you purchasing Plan B the following morning.

Myth #9: Women have a higher libido than men.

It's actually the other way around. Men purportedly think about sex more often, masturbate more and seek more casual sex than women, according to a WebMD report. A male's primary concern during sex is the knowledge that they will be physically stimulated; females, on the other hand, need to feel a significant decrease in their anxiety – the female sex drive is based largely on atmosphere, context and environment.

Myth #10: Wearing socks during is weird.

A study by the University of Groningen has shown that cold feet occur in more than just an apprehensive sense. "When they gave the couples socks to wear," said Michelle Roberts in a summary of the study for the BBC, "about 80 percent of the couples were able to achieve orgasm compared with 50 percent previously in this staged environment."

Myth #11: Having sex in a hot tub prevents pregnancy.

The increased temperatures in hot tubs and Jacuzzis doesn't kill sperm, contrary to popular belief – though soaking for more than 30 minutes at a time may lower sperm count, having sex in a hot tub does nothing to prevent pregnancy. Neither does altering your position during sex; if sperm can reach an egg from any given stance, then pregnancy could occur, and it's best to use other, more reliable contraceptives to prevent it.

Myth #12: Male nipples are superfluous.

False! Male nipples tend to function much the same as their female counterparts during foreplay and sex. While some men experience varying degrees of nipple sensitivity, Glamour magazine advises you to feel out his tastes with some gentle rubbing and licking – try to avoid biting, because a little can become too much fairly quickly and send your foreplay down in flames.