Evolution of a Joke

When Millie was just beginning to talk more, somewhere between 18months and 2 years, her father would joke around with her and say, in his best Darth Vader impersonation voice, "Luke, I am your father." She would repeat it over and over because it always got a laugh. It seems like it's been over a year though since the joke was in circulation. Last week at the dinner table though it resurfaced with a Millie twist:

Daddy (in Darth Vader voice): Luke, I am your father.
Millie (in baby Vader voice): I want some milk... I am your daug-tuh.