What is She Saying?

Spencer is trying to tell me something- I just don't know what it is. She says the same thing to me, over and over again, "Cac-ke, isssshh shhhhhyyy booo ka!" She looks at me like "why don't you know what this means?" It gets louder and louder and more insistent, but I don't know what it means.

If I repeat it, she laughs and jumps up and down, obviously elated that I'm on to what she wants. This usually turns to tears when she realizes that I don't know what she's saying, I was playing a joke a on her by pretending that I did.

It must really suck to be a baby.