London CAN is a phrase used to describe the city of London, England. It is derived from the two words 'London' and 'CAN', which are both three letter words. The first word, LOO, is an informal British term for a toilet or lavatory. The second word, TIN, is a noun that refers to a thin metal container used for storing food or other items. Together, these two words form the phrase 'London CAN', which is a popular way to refer to the city of London.