dee-donk, n. — Green’s Dictionary of Slang

dee-donk n.

also deedonc, didonk

[Fr. dis donc, so tell me. Note antecedents in the synon. didones (used in Spain after the Peninsular War (1808–14), a century earlier), dido (as used in Ling. Fr.) as well as, somewhat later, the Javanese orang deedonc, ‘the dis donc people’]

a Frenchman.

1918		Literary Digest 25 May 48: To the Americans, the poilu has become a didonk, and the term is used quite affectionately.
1929		E.S. McCartney ‘Sl. and Idioms of World War’ Papers Michigan Academy of Arts & Sciences 10 n.p.: Deedonc (Am.), Frenchman.
1933		Partridge Slang To-day and Yesterday 432: Dee-Donk. A Frenchman: [...] from dis donc, from which, perhaps, derives the American say! [...] (—1845) .
1960, 1975		Wentworth & Flexner DAS.