"Wie ich zu sagen pflege..."

J came out with this fancy expression (translation: "As I'm in the habit of saying") in the course of normal conversation this morning, something like: "Papa, wie ich zu sagen pflege, wann immer so was passiert..." I asked him where he picked it up, and he pointed to this scene in Asterix als Legionär:

Also yesterday he used the expression "I beg to differ," which he said he learned from Calvin and Hobbes.