I agree-- took me a long time to get that joke. And GOB is my favorite character as well.
GOB: "Listen, I don't have a son. [Narrator: He does.] But if I ever do, I'm either gonna take him to the cabin in the woods, or I'm gonna promise to take him and then not take him. But the one thing that I will never do, is not tell him that I'm taking him to a cabin in the woods, and then not take him! " Narrator: "GOB was growing up."