"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."