`` i was teaching sunday school one day and found that two boys , two very naughty boys , were giggling over an assignment , one of the book of job , which i never found particularly funny , and upon peering at their book from behind them , i found something quite different therein ... '' i know what 's comin ' here ... just like ned and tom and their navigation book ... `` what they had was a copy of a penny-dreadful book called bloody jack : being an account of the curious adventures of mary jacky ' faber , ship 's boy .