Many people think, this euphemism for having sex, is based on the analog of a metal screw and how a guy seems to be driving that screw in, when experiencing intercourse... but few realize at its start it was a farm expression, and describes the shape that many beast penises take when erect... such as pigs. Which also explains why we have the phrase, 'porking'.
Unconsciously perhaps, this also accounts for why sex is so exciting (beastal, animalistic, natural, basic, lower brained, automatic, lust driven, unintellectual, etc. ) and so disrespected.... same reasons as just stated for exciting.
They screw like animals.
They are so screwed!!
Ewww... they are such pigs! They screw everywhere with no concern!
Screwing is so... animalistic!
Oddly, many remember this expression as a term used in describing music i.e. This is screwed music, or this tune is screwed... without realizing the basis of it.
In the 'old days' mechanical turntables were used to 'play' 'records'. These had an adjustment screw which allowed one to set its rotation speed to a calibrated reference, to maintain 'high fidelity', (usually a radial pattern was put on the turntable and a 60 hz lamp made a standing wave pattern which visually allowed a user to synch the speed to the lamp). The 'screw' which was actual a 'bolt', would move an internal cone, and attachment to the spindle of the drive motor, and there a transfer wheel rubbing on the inside of the bottom of the turntable wheel, would press on it. Thus turning the screw, forced the transfer wheel to locate itself along a different conic radius, spinning the record at a different speed.
As the 'art' of 'playing a record' evolved, the use of this 'screw' to imply a taste onto the record playback, through its speed, became popular. Some turntables were later offered with servo (electromechanical) screws, so that speed modification, could be encoded and programmed, for repeatable shows. It was first merely a technology, which turned to art, and then converted to an appreciation of the result, which made this term popular... then, the term... became separated and self standing as slang.
Using the calibration screw to adjust turntable speeds:
We bang screw when were fucked up.
Down South We bang screw all day and night