London Underground service. Holds the unfortunate title of the "brown line" on the tube map.
It is possible to go to Baker Street and Waterloo on the Bakerloo line. Baker (Street) + (Water) loo = Bakerloo. In an alternative reality it may well be known as the Streetwater Line. Frikipedia loves the London Underground Logic.
The Bakerloo line is actally quite nice, if a little pointless in it's destinations, and achieves a ECUC of just 15%.