Doggone

I'm so doggone exhausted, I can't even think straight.

I lost my doggone keys again!

"Hist!" exclaimed Black George. "I'll be dog-gone ef [if] I don't think we're chawed [chewed] up this time, sure as sin!"

Doggone! I lost my keys again.

[…] doggoning something or other with deep sincerity.