Green’s Dictionary of Slang

(US) to go away, used as a command.

1931		C. Ford Coconut Oil 95: Blow. Ewscray. Circulate. Scram.
1939		in W.C. Fields By Himself (1974) 330: How could anyone hurt themselves falling off a trapeze? Ewscray.
1988		Maddock & Wilson Short Circuit 2 [film script] Ewscray, ouyay, ozobay!