It's just emphasis, for a noun. doggone INFORMAL•NORTH AMERICAN adjective used to express feelings of annoyance, surprise, or pleasure. Here as the song is between two guys claiming the same woman, it is "annoyance".

It means “God damn” 😀😀

I run a group on Skype called Explicable discussion. we are 3-4 people in the group who take the random topic to discuss every day. if you are interested in, tell me I will add you there happily. it is good to improve communication skills, listening and knowledge, so I started.

These days, it would be considered disrespectful.

A synonym might be: darn, or damn. I think its a very American saying. Perhaps southern United States.