For those of us who are non-theists and wish to purge our personal vernacular of religious terms, it can be difficult to get away from the conventional terms/colloquial expressions of "oh god," "my lord," and the like.
I propose its use as a basically meaningless term used for emphasis and/or exasperation in both writing and speech.
It serves as a transition away from "god" and "lord," but is still intuitive enough that the reader grasps the emotional content expressed by/with its use. Serendipitously, "gourd" being used as a replacement for "god" and "lord" is contextually nonsensical...a perfect reflection of the metaphysical silliness represented by the notion(s) of "god" and "lord" to the non-theist.
Dave: Well he is a perfect example of what I call a gourd.
Mike: Oh, you mean like the stupid vegetable that you cant eat, and looks ugly.
Dave: Yeah, that's the one. I try to avoid people like that.