Green’s Dictionary of Slang

Ivan n.

[the stereotypical Slavic/Russian name]

a generic term for a Russian; thus a Communist.

[[US]Record-Union (Sacramento, CA) 12 Nov. 8/3: Ivan Ivanovitch (pronounced Ee’vn Eevan’ovitch), a Russian].
[[UK](con. WWI) Fraser & Gibbons Soldier and Sailor Words 129: Ivan: The everyday name in the Russian Army, at any rate down to 1916, for a private soldier].
[US] Amer. N&Q June 48: The airmen [...] began to refer to every young Russian aide as Ivan.
[US]W. Winchell On Broadway 4 Sept. [synd. col.] The U.N. has quietly bounced 13 officials known as pro-Ivans.
[UK]T. Blacker Fixx 294: Get Ivan off my case.
[UK]J.J. Connolly Layer Cake 235: Are these going to Moscow? Gets the Ivans and Ivanas livened up?
[US]J. Ellroy Widespread Panic 76: ‘I won’t say no to some Ivan’s Lubyanka stash’.