What does yellow discharge on underwear mean?

Female or male?: If female - very light to white discharge might be related to leukorrhea. Leukorrhea is normal vaginal discharge (d/c). D/c is composed of cellular debris, vaginal secretions ; bacteria ; is stimulated by ^ vaginal blood flow ; ^ estrogen. D/c ^ is seen w ovulation (clear/stretchy), clear/watery or white d/c both occur during menstrual cycle.; pregnancy (white/ milky). It can be thin or thick ;.