Green’s Dictionary of Slang

McAtah n.

[W.I. pron. of (Douglas) McArthur (1880–1964), US general]

(W.I.) mirrored dark glasses.

[WI]M. Thelwell Harder They Come 311: A pair of mirrored aviator shades of the kind they called ‘cool-too-bad’ or McAtah, after the American general.