From a view source of a youtube page, SRSLY_GTFO.

yt.setMsg({ 'BAD_RESPONSE': "Bad response from server.", 'UNABLE_TO_CONTACT_SERVER': "Oops! Unable to contact server." });

      yt.setMsg({
    'ERROR_WHILE_PROCESSING': "Error while processing your request.",
    'UNKNOWN_ERROR': "An error occured while performing this operation.",
    'POSTING_COMMENT': "Adding comment...",
    'CONFIRM_NAVIGATE_AWAY': "Are you sure you wish to continue?",
    'CONFIRM_UNSAVED_CHANGES': "You have unsaved changes. If you continue, your changes will not be saved.",
    'FLAG_DEFAULT': "Select a Reason",
    'SRSLY_GTFO': "This will remove the selected user.  Are you sure you wish to continue?",
    'THEME_LIMIT': "You have reached your channel customization limit.",
    'CONFIRM_UNSAVED_CHANGES_ARRANGER': "You have unsaved changes. Are you sure you wish to continue?"
  });