Narg

The narg was a unit of currency used by Androgums in the Third Zone.

History
According to the Second Doctor twenty-narg was of sufficient value to cover a bill of 81,600 pesetas with change in 1980s Spain.

When Oscar Botcherby, a restaurant manager in Seville, refused to accept the currency Shockeye was aghast, remarking that the narg was negotiable "anywhere in the nine planets.", (TV: The Two Doctors)

The Seventh Doctor carried a twenty-narg note, among the various currencies in his pockets. (PROSE: First Frontier)

Behind the scenes
The narg is a tongue-in-cheek allusion to stereotypical ignorant British and American tourists attempting to pay for purchases with sterling or US dollars while holidaying abroad.