"restore to order," 1911, from un- (2) "reverse, opposite of" + scramble (v.). The original use is in a quip attributed to U.S. financier J.P. Morgan (1837-1913) about the impossibility of unscrambling an omelet.
Mr. Morgan is credited with the aphorism that the recent trust decisions are like an order to a cook to "unscramble" the eggs which have just been prepared. [Proceedings of the Academy of Political Science, January 1912]
Related: Unscrambled; unscrambling.