doggonit is used to express to another human one is frustrated with there actions, and would like to hit them upside the head but wont because it is rude.
Mildly pissed. You have been slighted, short changed, given promises by a woman, and she forgot all about the promises. A more refined, mannerly way of letting someone know you're pissed than saying Doggonit.
I was promised a supply of very upscale meats and cheeses, and Daggonit she gave it out to everyone but me. Hope they all get diarrhea.
Person 1: Hey Doggo. You like DDLC, eh?
Doggo: Yes.
Person 1: Then you should be shipped with Monika cause you like everything.
Doggo: And what will the ship name?
Person 1: Doggonika.
Doggo: ...