Do you catch the first train that comes? What if the station has six platforms? How do you decide which station to get off at? By drawing a card? Tossing a coin? Do you go outside and take photos, or do you stay in the system all day? Do you leave a trail? Does it take place on 4th February every year? Do you pick a cute man/woman/badger in your carriage and resolve to get off at the same station? What if they resolve to follow you? Are you allowed to take the DLR? South West Trains from Vauxhall to Waterloo? A 133 from Brixton to Elephant & Castle? What happens if you bump into a fellow Random Tube-Traveller?