The Odd Couple was a stage play written by Neil Simon in 1965. Its two main characters, Felix Unger and Oscar Madison, were friends with divergent personalities forced to share an apartment in New York City. It achieved popularity in American culture in the late 20th century, and was adapted as a film and a television series.
While attending a genetics conference in Rome in 1974, Roberta Lincoln noted a pair of suspicious strangers following her made more of an Odd Couple than Felix and Oscar. (TOS novel: The Rise and Fall of Khan Noonien Singh, Volume 1)