Pre-ejaculate, also known as pre-cum, is the liquid that seeps from the tip of the penis during sexual excitement before ejaculation happens. This fluid helps coats the urethra and helps sperm move. If there are sperm in the urethra from a previous ejaculation, then pre-cum could push them through the penis before a guy actually comes. So, it's possible for pre-cum to carry a sexually transmitted infection or cause pregnancy.