Green’s Dictionary of Slang

where the five’n’arf...? phr.

[rhy. sl.; 5½ yards = one rod (unit of measurement) = God]

where in God’s name?

1930		J.D. Strange Price of Victory n.p.: Where the five’n’arf you been, y’ little skunk? [DSUE].
1984		Partridge DSUE (8th edn) 1327/1: [...] C.20.