Green’s Dictionary of Slang

1. pertaining to Japan, the Japanese or Japanese culture.

1942		Time 23 Feb. 52: Many is the chaplain, dodging dive-bombers, who has gotten up waving his fist at the unopposed Nip flyers [DA].
1957		(con. 1944) A. Myrer Big War 300: It’s a Nip routine, I’m telling you.
1967		(con. 1940s) M. Dibner Admiral (1968) 26: Goddam gooks, Nip spies with transmitters.
1974		(con. 1940s) E. Thompson Tattoo (1977) 4: Seeing his own death on the long, cold steel of a Nip bayonet almost moved him to tears.
1979		P. Reading ‘It’s a Small World’ in Fiction 12: Wayne meets Jane outside the Nip Embassy.

2. pertaining to East Asia, East Asians or East Asian culture.

1993

B. Moore Lex. of Cadet Lang. 245: usage: ‘Nip food means Asian food, Vietnamese, Thai, and such like that’.