This is Why You Never Muck Your Hand Before the River

After a jack-high flop, two players are all in. The first player to show flips over pocket aces and his opponent tosses his cards into the muck. The dealer retrieves his card out of the pile and turns over two kings.

The players with aces was furious, saying the cards can not be pulled out, but after a floor person ruled that in an all-in both hands must be shown, the cards stayed out of the muck as the remainder of the hand was played out.

The turn was a complete blank, however....

The river brought a king.