Let me set the scene:
The Kiddo is playing in his room. I am in the living room. Then I hear a jump on the bed.
Me: Don't jump on the bed.
Kiddo is still playing in his room. Soon I hear another jump on the bed, although this one is quieter.
Me: I said don't jump on the bed.
Kiddo: How did you know??
Me: Because I'm smart.
Kiddo: Don't be smart.
When he says "How did you know?" I'm always tempted to say "Because I know EVERYTHING!!!" Followed by some form of maniacal laughter . . .
But I don't want to lie to him. Haha. You know, or scare him. Haha. It's still fun this way.