Cowper's fluid

Pre-ejaculate (also known as pre-ejaculatory fluid or Cowper's fluid) is the clear lubricating fluid that is issued from a man's penis when he is aroused. Slang terms for pre-ejaculate include pre-cum and speed drop.

The fluid is usually secreted by Cowper's glands during foreplay or at an early stage during sex, some time before the man reaches orgasm and semen is ejaculated. Pre-ejaculatory fluid prepares the urethra for semen and neutralizes any traces of urine. It also lubricates the movement of the foreskin over the glans. The amount of fluid that the human male can issue varies widely between individuals, from imperceptible amounts to a continuous stream.

A problem for couples who seek to avoid pregnancy, however, is that the pre-ejaculate may contain sperm. This is one additional reason why withdrawal (coitus interruptus) is not considered to be a reliable method of birth control.