Fortunately there's noise during zombie apocalypse movies. If you're going to orgasm loudly, it might as well be during a shoot out scene.

Chuck swallows hungrily, digging his fingers into Raleigh's thigh. He keeps swallowing to stop his gag reflex, pulling his hands out of Raleigh's pants and curls it against his hip as he finishes, letting his chin Reston the seat between his thighs.