His older brother was just "O" for the longest time till he became "amu". I am now "mama", "mummy" or "mum" depending on his mood and Aswin is of course baba. He learned "daddy" from a TV show recently and immediately implemented it.
"Daniel Tiger's Neighborhood" on PBS is his favorite TV show and yesterday I saw him use his toy phone to call "ne ne" Daniel Tiger and talk, nod his head and say bye before putting the phone down.
It also means he can now say "no" to a lot more things as well. Nap time- "no", pull up change- "no", eat your food- "no".
In short, he's quickly becoming a an opinionated little person.