beast with two backs

Etymology
First attested in English by, see quotations. Supposedly a (in modern French, la bête à deux dos) from , 1534, by.

Noun

 * 1)  Two people united in sexual intercourse in the missionary position.

Synonyms

 * See also Thesaurus:copulation
 * See also Thesaurus:copulation
 * See also Thesaurus:copulation