To play for keeps is to retain, on the winning side, what is played with.
1886. We, the undersigned, promise not to play marbles for keeps, nor bet nor gamble in any way.—Advance, Dec. 9 (Farmer).
1890. I jest put up the ol’ horse-pistol for keeps.—Mrs. Custer, ‘Following the Guidon,’ p. 315 (N.Y.).
1909. The five saloons are closed…. And there are no crap games “for keeps,” because there is nothing worth keeping.—N.Y. Evening Post, Feb. 4.
1909. [The productions of the American press at the time of the evacuation of Cuba] almost universally expressed the warning: “Now be good, or we will come back next time for keeps.”—Id., April 19.
