100 words. The first thing to fill my mind.
His hand steady at the back of her head, gripping then relaxing in time with his thrusts. Pressing forward until he hits the back of her throat and then back to rest on the tip of her tongue.
Her hands rest loose on his hips. Relaxing her throat, she moves forward a little bit more, inviting him deeper. Gripping his hips on his next ingress, she swallows around him.
The reflexive movement of his hand in her hair makes her cunt twitch. She swallows again, relishing the way his head falls back and the deep groan that leaves his lips.