Input (grade 12): Jonathon Green, The Cassell Dictionary of Slang, 1998, page 1110 The game is also known in Australia as soggy Sao after the SAO brand of biscuits popular there.
Output (grade 9): Jonathon Green, The Cassell Dictionary of Slang, 1998, page 1110 The term is thought to have originated in Australia sometime in the 1960s.