隔壁老王

Mr Wang from next door (term used jocularly to refer to a neighbor who is supposedly sleeping with one's wife)

to separate / to partition / to stand or lie between / at a distance from / after or at an interval of

next door / neighbor

wall / rampart

prefix used before the surname of a person or a numeral indicating the order of birth of the children in a family or to indicate affection or familiarity / old (of people) / venerable (person) / experienced / of long standing / always / all the time / of the past / very / outdated / (of meat etc) tough

king or monarch / best or strongest of its type / grand / great

to rule / to reign over