Ten Days in a Mad-House

Nellie Bly walked in to the office of a major newspaper and became an undercover journalist overnight. It was her idea to feign insanity and get herself committed to an asylum in order to write about conditions in the institution. From Wikipedia:

After a night of practicing deranged expressions in front of a mirror, she checked into a working-class boardinghouse. She refused to go to bed, telling the boarders that she was afraid of them and that they looked crazy. They soon decided that she was crazy, and the next morning summoned the police. Taken to a courtroom, she pretended to have amnesia. The judge concluded she had been drugged.

She was then examined by several doctors, who all declared her to be insane. "Positively demented," said one, "I consider it a hopeless case. She needs to be put where someone will take care of her."

The caper brought Bly overnight fame and led to reforms in the system. She wrote a book about her experiences, Ten Days in a Mad-House, which you can read online. Bly went on to other adventures, as you can read at TYWKIWDBI. Link