The devil’s tango is a humorous and old-fashioned euphemism for sexual intercourse. It reflects some interesting facts about American and British culture, especially before the 1960s.
The tango is a dance style for couples, in which the dancers press their bodies together and move back and forth in a somewhat sexual and athletic manner. The dance developed in South America, between Argentina and Uruguay, and came to the US and Britain in 1913, becoming very popular. It was developed partly by African-South Americans and the word tango may come from an African language of the Niger-Congo language family.
The phrase devil’s tango reflects the strongly anti-sex teachings of much traditional American and British Christianity. Sex was, and to a large degree still is, considered a sin by many people, and therefore, of the devil. Moreover, the tango, like other South American dance styles, may be seen as highly passionate, or even overtly sexual, to many Americans and Brits.
So, the devil’s tango reflects both negative and positive feelings about sex and the sexiness of South American dance traditions. However, the phrase has probably always been used humorously.