parlor pink: someone who expresses socialist views, but is not politically active, especially someone of the upper classes
This term first began appearing in print in the early 1920s. A 1925 volume of Manufacturers News refers to "socialists, welfare workers, parlor pinks, and liberals." The expression may have been inspired by Theodore Roosevelt, who coined the term parlor pacifist in a 1917 book titled The Foes of Our Own Household. The following year he used the term parlor bolshevist in his book about World War I, The Great Adventure: ". . . our own moral fiber is weakened by the parlor or pink-tea or sissy Bolshevism." Roosevelt distinguishes parlor bolshevism—the kind that sympathizers champion from the safety of their parlors—from the "gutter" bolshevism that true believers actively fight for.
By 1920 the snappier term parlor pink was appearing frequently in newspapers and magazines. Pink and pinko entered the vocabulary around this time to signify someone less radically left than a red. Fellow traveler, another slang term for those with leftist sympathies, also first appeared in the 1920s.
Although parlor pink disappeared when parlors went out of style, pink and pinko are still part of the vocabulary. They were especially popular during the 1950s era of reds under the bed.