In an unexpected twist, my roommate waltzes into my room and without a word, straddles my lap, grinding her luscious ass against my crotch. Her thick thighs squeeze my waist as she bounces, her generous curves jiggling with each movement. My hands instinctively grab her hips, pulling her closer, feeling her heat through our clothes. She leans back, her head resting on my shoulder, her breath hot on my neck as she rides me, her big tits heaving with each thrust.