This is from a woman on Tumblr named jessicaobeys.
"Well, I can’t speak for those some or most men however maybe you could apply Newton’s 3rd law to the following:
I am interested in it because of how submissive it makes me feel.
No one is allowed to see your bum because #politesociety except for your waxer or doctor. So having anyone else even look at your most private hole (much less touch/use/penetrate/stretch it) is a big thing. They are literally invading parts of you that you don’t even look at on a regular basis (unless you hold a mirror there all the time).
Also, aside from when going poopy, your tiny bumhole isn’t meant to open in that manner. Having to submit your bottomhole to penetration and stretching to something large and invasive is so UNF to me I’m not even sure how to explain it. Being fucked in the bottom to me is probably the most submissive act ever. Having to accept the discomfort. Having to endure the discomfort. Being a good girl despite it.
To have your soft, warm, squishy, tight bottomhole penetrated to please someone. Being pliable to their demands. Accepting their control.
And in the same vein: Accepting and retaining butt plugs/cucumbers/enemas/soapsticks. Same idea plus more - adding discomfort on top of penetration. Training, discipline, punishment and reward to meet someone else’s standards.
That probably wasn’t very cohesive but that’s the best I can do at this moment because…
Excuse me while I go deal with my leaky kitty."