Juicy, google the phrase "yellow color to semen" if you want medical sites to load up instead of the huns yellow pages, lol
Heres an excerpt:
Yellowish or green color to your semen. Normal semen may have an off-white or yellowy hint to the color. Where semen is uncharacteristically yellow or greenish in color it is a sign of infection, often due to the sexually transmitted disease, gonorrhea. Go to your local STD clinic, treatment is simple with antibiotics.