Power couplings were important parts of starships.
The term also referred to devices used to power objects on planets, such as the power coupling Anakin Skywalker and Obi-Wan Kenobi flew through in their pursuit of Zam Wesell on Coruscant. Power couplings were used to hold podracer engines together and transfer power between them.
"Hooking up a power coupling", while perhaps not consistent with the actual assembly of the device, was regardless used by several companions of the Jedi Exile to describe intimate relationships and presumed sexual intercourse.