Eet Ees FunnE!
na-nee (from na-na, her word for pacifier)
All of these words are said frequently (in context) and with great glee. The only possible explanation that I can think of is that we thought "hummy" was absurdly cute and she overheard us telling one of our parents about it, so perhaps she is INTENTIONALLY doing it to please/impress/manipulate us. But that would be scary. Also, we don't react to the other "ee"s and she does not appear to be checking out our reaction or lack thereof. So I will banish the thought and revel in the cute absurdity instead.