However, the origins of this phrase are not entirely clear It is believed that the term first came into use in the 1960s during the height of the sexual revolution. A person obsessed with sex 'sex machine' is an english idiom It is a playful or colloquial term used to describe a person who is skilled or highly successful in sexual activities or relationships. There is one meaning in oed's entry for the noun sex machine
See ‘meaning & use’ for definition, usage, and quotation evidence. (idiomatic) someone with considerable <a>sexual</a> <a>prowess.</a>.
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