Pre-cum is the clear liquid that seeps from a man's penis when he gets aroused. It is actually a natural lubricant.
This link will best explain it. There is some question on getting pregnant from pre-cum. This doctor explains that is very unlikely that anyone can get pregnant from this pre-cum, as it would have to have sperm in it. Sperm are only released upon ejaculation. Since pre-cum forms before ejaculation, it is highly unlikely that anyone will get pregnant from a little pre-cum.
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