Eldest: Dad, how long did it take for them to build Big Ben?
Dad: I don't know. I don't even know when Big Ben was built. I know nothing about Big Ben.
Mom: Mark it on the calendar, son. That is one thing you won't often hear your dad say.
*conspiratorial look from dad*
Eldest: What? That he doesn't know about Big Ben?
Mom: That he doesn't know anything about something.
Meanwhile, Dad, who is searching for plane tickets online suddenly opens another browser, presumably to look at where Gojjo Ethiopia is, when what to my wondering eyes should appear but the Wiki page for Big Ben.
Mom: Oop. Too late. The time has passed.
Mom glances at calendar to see what tomorrow holds. Today's date says, "Dad doesn't know something."