He thrusts his cock into her anus all at once; they move their hips back and …

Prompt

He thrusts his cock into her anus all at once; they move their hips back and forth; his cock plunges deep inside her and pulls out completely again—a hard, steady fuck; her ass shakes with each thrust; his cock stays hard; her anus stretches around his cock; her ass bounces with each thrust; she pushes herself against him with a rhythmic and energetic movement of her hips