A: This sounds like the Wiggles.
E: This is not a Wiggles song.
A: Maybe it is a Wiggles song.
E: A, you haven't listened to the Wiggles in like 4 years. You don't know.
Me: It kind of sounds like the Wiggles. It could be a Wiggles song.
A: Yeah, E. How do *you* know it's not a Wiggles song.
E: I just know, A.
(During this conversation, "Cherry Cherry" has ended and "Lady Marmalade" is now playing.)
Me: E, do you listen to the Wiggles? How do you know they didn't cover this song?
E: The Wiggles did not cover "Lady Marmalade".
Me: We weren't talking about "Lady Marlamade", we were talking about the song before it, the Neil Diamond song.
E: Oh. I didn't hear that song.
Me: Wait a minute. You didn't hear the song yet you stated that you knew, without a doubt, that it was not a Wiggles song?
E: Well, yeah.
And that's the absolute certainty of knowledge, as possessed by a 14-year-old.