It's vulgar to want to insert things into someone's butt.
Joel just started to date a woman and takes her back home one evening.
Joel wants to have hot sex.
Joel considers asking his girlfriend about sticking things up her butt but decides against it and asks her about her favorite fantasy instead.
Joel insists on sticking things up his partner's butt.
Joel's girlfriend is excited to share her fantasies with Joel and has a great time.
Joel's new girlfriend accepts but thinks he's vulgar and gross.