surprise

• Out of the blue

  Something that happens completely unexpectedly or without any prior warning.

• A bolt from the blue

  A sudden, completely unexpected event, often one that is unpleasant or shocking.

• Have the rug pulled out from under someone

  To suddenly and unexpectedly remove a crucial support or advantage, leaving someone in a difficult or vulnerable position.

• Pull a rabbit out of a hat

  To produce a surprising, unexpected, or ingenious solution, item, or outcome, often as if by magic.

• Without warning

  Occurring suddenly and unexpectedly, with no prior notice or indication that something is about to happen.