Hiding messages that are published online. The topic was popularized in an article by Microsoft researcher Danah Boyd in 2010. She cited an example of a young girl posting lyrics to Monty Python's "Always Look on the Brighter Side of Life" to keep her mother from knowing she broke up with her boyfriend and getting overly involved. In the Monty Python movie, people were about to be killed when the song played, and the girl's friends, hip to the movie, contacted her independently. See
steganography.