She lustfully grasps your smooth crotch and disrobes. It feels so weird not feeling a dick there. You wish you still had one so badly. You keep staring at Alex's flat chest, her smooth crotch with nothing but an outlet for urine.
You tell her, "I'm not able to fuck you!"
She seems confused, "What do you mean?"
You realize the idea of not being able to fuck must be alien to her. You say, "you've told me about people aciendently swapping universes?"
She seems even more confused, "yes?"
"I'm from a different universe. One where people have special body parts to be intimate with."
"For real?"
"Yes"
She seems nervous, "Well, you're worried you can't fuck like this? Because we fuck here without any 'special parts'. I'm sure you can be happy here."