Used when angry or suprised, but not so angry/surprised that you forget that an authority figure (i.e. The Man) is in hearing range.
Common in the Diana Tregarde Series by Mercedes Lackey, which is about urban witch Diana's occult investigation service.
Diana: Jesus Cluny Frog! *Hits the brakes* What was THAT?!
Bum: *Knocks on window* Spare change, ma'am?
Di: Oh... sure, I--
Bum: *Gets eaten by large demon*