Re: What is this!
I agree with Marie that you should definitely have it checked out.
You used the word nipple in the plural. If the discharge is from both breasts, that's usually a good sign in that cancer doesn't usually present itself bi-laterally.
Some causes (apart from cancer):
History of breastfeeding: Some women produce a milky discharge months and sometimes years after having finished breastfeeding.
Stimulation: Squeezing or expressing the breast or nipple can produce a nipple discharge.
Fibrocystic breast changes: Cysts (sacs filled with fluid) and changes in the fibrous tissue of the breast can cause nipple discharge.
Intraductal papilloma: This is a small benign wart-like growth in the duct lining.
Hormonal changes: An increase in prolactin.
Discharge from one or both nipples is a very common finding believe it or not. It's very rare that nipple discharge is related to breast cancer.
But again, you shouldn't ignore it. See your gynecologist.