Rachel, meet evil Olivia

Yesterday our sitter got her first "real" taste of the other Olivia - usually reserved for Alan and I.
When Rachel brought Dan down from his nap, Olivia was coming upstairs from the basement. When they met in the kitchen Olivia started to cry because she wanted to go see Dan in his crib (she likes to greet him when he wakes from his nap)... Awww, cute, huh?
Not quite - Olivia will not stop crying. Rachel is trying everything and then asks Olivia if she wants to go upstairs to her room to try and calm down. "No." Now Olivia is getting angry and saying an arbitrary "No" to everything Rachel suggests. Rachel tells her to go to her room for a bit. "No." What to do? Rachel tries to talk to Olivia and then..."I don't like you. I'm going to punch you." WHAT???
Where did she get that? Alan and I were racking our brains last night to see if we had ever talked about punching one another in front of her... We cannot figure this one out. So, once again I sit and try to explain the rather mature concept of Threats to a three-year-old. And what does she say to me as I am explaining that we consider that really bad behaviour? "All right, all right, all right..." Grrr.
What have I been saying in front of her? I don't think punching comes from Treehouse, much as I'd like it to be the root of all evil and take the blame for me.
I admit i would have been less shocked by the f-bomb being dropped. That one definitely slips out despite a solid effort on my part to clamp down on it.
I still say she is a remarkably good child like 90 per cent of the time, although it is nice to have a third party witness our "other" Olivia for once.
Take care,
V