The term "Bakerloo Line" is used in English slang to denote the activity of
anal sex, due to the Bakerloo being coloured
brown on the
London Underground map. In the same vein as the "
Marmite Motorway" and "
Bourneville Boulevard" the term offers the ability to
snigger like a schooboy for those who know this subversiveness, whilst keeping the
gentile innocents unoffended.
Example : "She wanted me to take her up the Bakerloo Line!" (best said in annoying cockney accent)