"Oop-a-dee" is Annabelle's way of saying, "whoops-a-daisy!". It's fun to hear her use this phrase correctly throughout the day.
Here she is coming upstairs in the morning just after waking up. Elisabeth and Annabelle are still sharing a room at night and it's going surprisingly well. Hooray!When she saw me at the top of the stairs she stopped, smiled and called out, "A-nonin!" aka 'good morning!'. I'm not sure how her sleep top got so twisted up like this in the night, but I suppose the 2T clothes she wears are still a little roomy and so things like this will occasionally happen.