Cute thread. DD calls it "dee dee" ... it started as "Drinkie drink" when DH and I would talk about it, before DD started talking. Then, when she started trying to ask for it verbally herself, it got shortened to dee dee.
Now it is as though my dee dees have their own personality. DD will kiss my belly (I'm 9 months pg) and say hello to the baby, and then kiss each breast and say "hello dee dee, hello dee dee" - it is as though I have THREE people living in there, not just one growing baby!!