She's not thinking about money, or her job, her friends, her obligations, or her responsibilities. She's not thinking. She's totally in the moment, his cock in her ass, her head underfoot. It's very zen. In submission, she's found Nirvana.
You may think getting your ass destroyed is an easy job, but sex is actually work to womyn, that is, something you can do and you do to obtain in return other things you can't achieve on your own. This is why sex workers exist; in fact, sex workers are th