The Ultimate Sex Quiz

Size matters: According to the British Journal of Urology International, men boast an average of 5.5 to 6.2 inches in length and 4.7 to 5.1 inches in circumference.

Good news, ladies: The clitoris has more than 8,000 nerve endings.

About 20 to 30 percent of men of all ages experience premature ejaculation.

You may think a glass of wine is getting you in the mood, but it's not. Exercise is far from being a libido killer; it's actually one of the best ways to kick-start your sex drive.

According to sex counselor Ian Kerner, women reach orgasm about 25 percent of the time with intercourse and 81 percent of the time during oral sex.

Thank your pudendal nerve for letting your brain know about the stimulation that the clitoris, scrotum and penis are receiving.

There's a reason they call it losing control -- the lateral orbitofrontal cortex is the seat of reason and behavioral control.

Love is a drug, and in the brain, heroin use and orgasm look almost completely alike -- 95 percent similar, in fact.

Many people think the ancient sex manual describes 64 sexual positions, but it describes 64 karma-kalas, or modes of love-making. The actual positions only number 18.

According to the CDC, chlamydia is the most frequently reported STD in the U.S., with 1,030,911 chlamydial infections reported in 2006.

Couples across the globe are having sex about 139 times a year! That's a little more than twice a week.

Without relief, men are said to experience blue balls. This name was penned perhaps due to the color of the testicles during this unfortunate experience.

During sexual intercourse or when the woman is aroused, the vagina swells to approximately 4 to 8 inches in length and 2.5 inches in width.

According to psychologist Gordon Gallup, PhD., semen appears to act as an antidepressant in women.

Althought it was popularized by a 1982 book, many doctors still debate whether the G-Spot actually exists.

The uneven blood flow during the process of vasocongestion, contributes to the penis becoming erect and causes the testicles increases in size by 25-50 percent.

Women do it too! Studies show that approximately 90 percent of men and 65 percent of women masturbate.

The time the penis is unresponsive - usually about 30 minutes or more - is called the refractory period.

The Bartholin's glands are at the vagina opening and release natural lubrication.

if you want to burn some calories, devote about 30 minutes to sex and burn about at least 85 calories.