1. When Tim went into his supervisor’s office, he thought he was going to get a raise for a job well done. He had the rug pulled out from under him when the boss fired him instead.
2. Anne pulled the rug out from under her parents when she told them that she was not going to medical school and had decided to get married instead.

Compare to: knock/throw (someone) for a loop. The expression suggests the feeling of shock a person would have if a rug was literally pulled out from under him or her.