Just because a guy has a penis doesn’t mean he knows everything there is to know about it, no matter how much quality time he spends with it. There are many penis facts - some basic, some obscure - that lots of guys don’t know (although hopefully they know enough basics to keep their penis health covered). And sometimes those penis facts can fall into the area of sex tips, which is something most guys are interested in. Not that most guys really ever need any sex tips, of course!

Still, for any guy curious to test his knowledge of penis facts and sex tips, the following can come in handy.

- Most guys don’t need huge condoms. Okay, so all guys like to claim that their members are incredibly massive. It’s just part of being a dude. But it’s important to not let that claim cause a guy to purchase the wrong size condom, just to save face. Only about 6% of men need the extra-large condoms - and if a guy isn’t part of that 6%, he needs to just face up to it. Wearing a condom that is too large means it might slip off during sex, or that it will be loose enough that semen might drip out - and that defeats the purpose of a condom.

- Size can be dependent on method of erection. Some studies have indicated that a man’s erection will be slightly longer when measured after oral sex or intercourse as compared to when measured after simply becoming erect through non-physical arousal. So it may pay to have a little round of oral sex before inserting into the vagina.

- The penis works all night. Most men average between three to five erections while they sleep. This nocturnal workout helps to keep the penis healthy, working on its tone and elasticity. Men who do not experience nocturnal erections may have some sexual function issues, and so should discuss any lack of nighttime erections with their doctor.

- Foreskin is rich in Langerhans cells. Langerhans cells, which are more susceptible to HIV, are abundant in the foreskin. This means that intact men need to take extra care (such as wearing a condom) to help prevent acquisition of HIV.

- Size dissatisfaction doesn’t always make sense. Many men who believe that their penis is too small actually have a penis that is of normal size - or even larger. It’s important to understand (1) that size matters only up to a point and that the vast majority of men have penises that are capable of providing pleasure, and (2) focusing too much on penis size, especially when one’s penis is of a decent size, can lead to sexual dysfunction.

- Smoking is bad for a penis. Some studies indicate that cigarette smoking can actually cause the penis to shrink a little. However, the bigger problem is that smoking can have a bad impact on circulation, making it more difficult for the penis to get the amount of blood it needs to achieve and maintain an erection.

One of the most important penis facts (which can also double as one of the sex tips): Guys need to take special steps to ensure their penis health. One of the most basic steps is to regularly apply a first rate penis health crème (health professionals recommend Man 1 Man Oil, which is clinically proven mild and safe for skin). The best crèmes will include an amino acid known as L-arginine. This ingredient is a crucial part of the process by which nitric oxide is produced - and nitric oxide plays a big role in keeping penile blood vessels open so they can accommodate increased blood flow. Also important in a crème is vitamin C, a key component of collagen, a tissue in the body that gives skin its tone and elasticity and is vital for penile erections.