It happens to most of us, hon. Welcome to womanhood. I think it's caused by the 'cowper's gland, or 'bulbourethral gland.
"The bulbourethral glands are compound tubuloalveolar glands, each approximately the size of a pea. They are composed of several lobules held together by a fibrous covering. Each lobule consists of a number of acini, lined by columnar epithelial cells, opening into a duct which joins with the ducts of other lobules to form a single excretory duct. This duct is approximately 2.5 cm long and opens into the urethra at the base of the penis. The glands gradually diminish in size with advancing age.
During sexual arousal each gland produces a clear, viscous secretion known as pre-ejaculate. This fluid helps to lubricate the urethra for spermatozoa to pass through, it neutralizes traces of acidic urine in urethra[2], and helps flush out any residual urine or foreign matter."
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"The Bartholin's glands (also called Bartholin glands or greater vestibular glands) are two glands located slightly below and to the left and right of the opening of the vagina in women. They secrete mucus to provide vaginal lubrication. Bartholin's glands secrete relatively minute amounts (one or two drops) of fluid just before a woman orgasms. The minute droplets of fluid were once believed as important for lubricating the vagina, but research from Masters and Johnson demonstrated that vaginal lubrication comes from deeper within the vagina. The fluid may slightly moisten the labial opening of the vagina, serving to make contact with this sensitive area more comfortable for the woman.
Bartholin's glands are homologous to Cowper's glands in males. However, while Bartholin's glands are located in the superficial perineal pouch, Cowper's glands are located in the deep perineal pouch."
