Rapt
Very happy or pleased.
Person 1"How did Kylie go with the new job?"
Person 2"Got it. She's rapt to the back teeth."
You'll also hear
Rapt to the back teethextremely pleased
Where it's from
Rapt is the Australian spelling of wrapped, as in wrapped up in something.

Something wrong or missing? Suggest a fix
While you're here
Extremely busy. Can be sarcastic about someone who isn't busy at all.
Extremely happy.
Get loud and rowdy, usually said of a party or a crowd. Also used for someone losing their temper.
Scare someone so badly they nearly wet themselves.
Extremely busy, with no hope of keeping up.
Completely exhausted or broken. Rooted means stuffed; gum trees have very deep roots.