Seriously. Just block out a short story that has sex in it, bang that shit out, and see how you feel about it. Thumbnail a short comic or something. Whatever your skill set works best for.

I also think there's an odd area where trans people especially are used to writing euphemistically, because our forms of intimacy are not often the literal (often very straight) version of sex, and working in metaphor is often rewarded with queer cred. Describe the blood! The spit! Whatever!