If the chicken I’m cooking leaks pink or red-tinged juices when I prod it with a fork, is the chicken safe to eat?

Many consumers associate pink liquid in packaged fresh chicken with blood. Wrong. It is generally a clear sanitizing solution absorbed by the chicken in the processing plant. Blood is removed from poultry during slaughter and only trace amounts may remain in the muscle tissue and  bone marrow. Improperly bled chicken is condemned at the processing plant.
 
However, according to food scientist Susan Brewer, “In general, if there is red juice (not blood), the chicken hasn’t been heated to 165°.”   That means keep it in the oven (or on the grill) a little longer. 
 
Sources:
hoptechno.com "Chicken -- Safety and Preparation"
Susan Brewer, Ph.D. University of Illinois, Department of Food Science and Human Nutrition