Empty carriage, only the rhythmic clatter and sex aerobic. She locks the door, strips, and straddles the seat facing the window. Moonlight paints silver across her skin as she chants “sex aerobic” in time with the rails. Four fingers stretch her open; the wet slap echoes louder than the train. “Everyone outside, see sex aerobic come,” she gasps. The train enters a tunnel—darkness swallows everything except her rising “sex aerobic, sex aerobic, fuck, sex aerobic!” until she explodes, soaking the leather in a flood of unstoppable “sex aerobic” release.