This is one of my favorite stories. There are three or four that I could cite as being what inspired me to start doing the comic strip and this is one of them. When he said, "Water," I almost died laughing. Becuase it's so perfect! He was absolutely, 100% correct - and yet gave me an answer I never saw coming!
I believe that, in his mind, we have to follow the procedure. And (silly, Daddy) you have to water the tree about 15-20 times before the presents go there!
(And the reason Iasked him what kind of tree it was is that he has grandparetns in Florida and was getting "pine" tree and "palm" tree mixed up; so I thought I'd test him. "Christmas" Tree was another answer that, while 100% correct, was totally not one of teh things I expected him to say.