Something that is surprising or different from what you would expect is unexpected. Things that are unexpected are usually not likely to happen, which is why they are surprising.
In the middle of the night, Jack awoke to an unexpected noise coming from the living room. When we came out of his room, he found his dog had knocked over the corner lamp.
The phrase expect the unexpected means that life can be surprising, so we should always be prepared for things that we do not expect to happen. People who expect the unexpected are open to the surprises life has to offer.
Fantasy and science fiction novels are so popular because they teach us to expect the unexpected. Maybe one day there really will be flying cars and life on other planets.
To surprise or deeply shock someone is to stagger them. Stagger can also mean to walk in an unsteady way. So, to stagger someone with information means to make them emotionally or mentally unsteady with surprise.
Anything that is shocking or very surprising is called staggering. If information is likely to cause emotional or mental shock in people, it is considered staggering news.
Since the staggering news about aunt Carol came out in the newspaper, everyone wants to come to our house. People can't believe the Prime Minister's own cousin lives in our town.
The results of Sheldon's experiment with the growth of plants was staggering. He discovered a way to make fruit and vegetables grow five times faster than normal.