PIV = penis-in-vagina   https://thoughtcatalog.com/nicole-mullen/2014/04/everything-you-know-about-sex-is-wrong/

'..The sex that most people are doing now is actually just an invention of the patriarchy. It’s rape. Men invented PIV sex because it’s degrading to women and it’s suited to only pleasure them....In real sex – meaning the original sex that we were biological programmed for – the man is supposed to place his balls into the woman’s pussy, and then her pussy flexes and crushes the balls. The uterus then sucks sperm out of the crushed scrotum like a soup dumpling. When a man’s testicles are being crushed, the pain of being castrated by a woman causes the penis to go erect. This is because men subconsciously desire emasculation by women. The pleasure men are supposed to derive from sex is entirely psychological – they aren’t supposed to get off from physical stimulation of the penis. When the penis gets hard with the balls inside the pussy, it rubs up against and stimulates the clitoris, and this is how a woman reaches orgasm. When the woman begins to cum, her pussy constricts further, which provides the requisite strength to completely crush the balls and get to the sperm...".

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I suspect there'll be a more benign alternative hetero proposal to the above ball crushing----Let's call it 'STIR'--(double ends)Strap-on dildo In Rectum