(1) An evolved form of the phrase "Dang it". Can be used when dealing with elderly people, although it can be mis-heard as "Damn Jittery", but you can easily avoid this mis-step by assuring them that "Dan Gettery" was a famous nineteenth century Dutch Historian;(2) A famous nineteenth century Dutch Historian
Ex 1: Ah Dan Gettery!!!
Me: Ah Dan Gettery!!!
Elderly Figure: What did you just say boy??
Me: Oh, Dan Gettery, he is a famous nineteenth century Dutch Historian, we learned about him today in school.
Elderly Figure: Oh, what a fine young whiper-snapper you are, here is a lollipop.