It's a quote from the disaster movie spoof "Airplane!" -- the entire flight crew has gotten sick from food poisoning, and the only other pilot they've found on board (Striker) is afraid of flying:
Rumack: Can you fly this plane, and land it?
Ted Striker: Surely you can't be serious.
Rumack: I am serious... and don't call me Shirley.
I don't recall if Dennis has ever laid out his complete workflow, though he does have a thread planning the 2009 (San Francisco) Bay Area OmniFocus get together at the end of this month, and I'm sure he'd be happy to explain it in detail if you attend :-)
As for the reluctance to split things into their component actions, Curt Clifton has penned a script that will automate this in his
Complete and Await Reply script. To quote from his description:
This one marks the selected action as complete and creates a new action, like the selected one but prefixed with “Reply on:” and placed in your Waiting For context. Great for email and other actions where you expect a reply.
Proof that I'm not the only lunatic who thinks these are separate actions :-)