I grunted. It's something I picked up over a fifteen-year career in law enforcement. Men have managed to create a complex and utterly impenetrable secret language consisting of monosyllabic sounds and partial words—and they are apparently too thick to realize it exists. Maybe they really are from Mars. I'd been able to learn a few Martian phrases over time, and one of the useful ones was the grunt that meant "I acknowledge that I've heard what you said; please continue.