Pre-cum or pre-ejaculate/pre-seminal fluid is the clear liquid that dribbles out the top of the dick during sexual arousal.
Pre-ejaculate is primarily produced by the Cowper's glands and we reckon it's purpose is to:
a.) neutralise acidity in the urethra (caused by pee)
b.) provide some extra lubrication for sexual activity and
c.) help out with semen coagulation
The amount of pre-cum produced varies dramatically from dick to dick with some not producing any at all.
Pre-cum is chemically similar to semen but has significant differences. The major difference being the presence of SPERM. However, low levels of sperm can be found in pre-cum and can potentially impregnate a woman if they are really determined and lucky.
Thumbnail image via Flickr