Get her done

Kurt and I joined Kristan & her family for a float trip on the Huzzah River, from Bass’ River Resort. Quite distinct from the tranquil Meramec rides of my youth, the river was packed with people.

As I put it last weekend at Six Flags, this was a different slice of the public than I am accustomed to. Beer bongs, mullets, and flabby exposed flesh were the norm. Kurt and I also noticed the prevalence of the phrase “get 'er done,” seeming metasyntactic in its use, as if it were the expanded form of “hey.” What does this mean? Where did it come from?