rycbar123 was a password used to access the Wi-Fi in the Maitland household in 2013.
Clara Oswald, the Maitland children's nanny, used the mnemonic "Run You Clever Boy and Remember" to remember the password. After Clara inadvertently contacted the Eleventh Doctor, asking for help accessing the Wi-Fi, her use of this phrase alerted him to her connection to the previous versions of Clara Oswald he had encountered. (TV: The Bells of Saint John)