There's this thing they have in French: L'espirit d'escalier. The spirit of the stairway. I don't think we have a word for it in English.
It means, well, the clever things to say that you only think to yourself when you're on the way out.
All the cool stuff you wish you'd said at the time. So I'm walking down the stairs, thinking:
"Firstly there's no such person as Death."
"Second, Death's this tall guy with a bone face, like a skeletal monk, with a scythe and an hourglass and a big white horse and a penchant for playing chess with Scandinavians."
"Third, he doesn't exist either."
"Fourth I'd say what you're doing is," Hell... All that stuff mom used to burble in her Freudian period which lasted for maybe a couple of weeks-- "You're blocking, or transubstantiating or something."
"Which is to say, you're nuts. Your walls do not go all the way to the ceiling. You are not playing with a full orchestra."
"You, madam," I would say, "Are a chocolate cream and a hazelnut suprise short of a full box of chocolates."
Sexton Furnival, Death: The high cost of living ~ Neil Gaiman