Dry zombie humor

So, watching the boys playing Call of Duty 5s "Nazi Zombie" mode. One son, fighting off the hordes, shoots a zombie right in front of him, it goes down but a bit slow. Me, knowing sometimes they get back up, ask him "Son, is it dead?"

Completely deadpan, without turning, boys says back,

"Dad, it's a zombie"

I know some wont get it, but I just lost it

but you always have to keep your eyes on the ground for the crawling torso's