A couple of days ago, when I was jocularly admonishing the bun, I said, "Duuuude." And he laughed. So I said it again: "D00d." He laughed even harder. "Duuuuude." The laughing was off the scale: he had tears streaming down his face and he was turning red. So I went to show his papa, who also said, "Doood," and he just kept on laughing. Now we say "Dude" all the time just to see if it still works.
I don't know what this says about the bun, but I hope it doesn't imply a tendency towards SoCal Surf-Speak. Or, god help me, that he'll grow up to be a bus driver like Otto on The Simpsons.