Interesting wiki article!

http://en.wikipedia.org/wiki/Male_lactation

The phenomenon of male lactation in humans has become more common in recent years due to the use of medications that stimulate a man's mammary glands. Though boys and men have nipples, many are unaware that they also have mammary glands. In ordinary circumstances, there is so little mammary tissue that it is unnoticeable; if the male breasts develop visibly, the condition is called gynecomastia. Under the appropriate hormonal stimulus—that nature provides to human females when they become pregnant and give birth—the mammary glands of human males can also produce milk.[1] The volume of milk produced is low relative to that of a lactating female. Newborn baby boys (and girls) can occasionally produce milk because of the intense hormones involved in their mother's pregnancy and the hours of childbirth; this is called witch's milk.

Male lactation is most commonly caused by hormonal treatments given to men suffering from prostate cancer. Female hormones are used to slow the production of cancerous prostate tissue, but the same hormones also stimulate the mammary glands. Male-to-female transsexuals may also produce milk owing to the hormones they take to reshape their bodies. It can occasionally be a side-effect of antipsychotic medication. Extreme stress combined with demanding physical activity and a shortage of food has also been known to cause male lactation. The phenomenon occurred in survivors of the liberated Nazi concentration camps after World War II.[1] Some American POWs returning from the Korean and Vietnam Wars also experienced male lactation. Among certain Pygmies in central Africa, anthropologist Barry Hewlett has observed children sucking nipples of adult males.[2] The phenomenon has also been observed in isolated cases in other parts of the world.[3]

The phenomenon of male lactation occurs in some other species, notably the Dayak fruit bat (Dyacopterus spadiceus), and the lactating males may assist in the nursing of their infants. In addition, male goats are known to lactate on occasion.[4]