If you know the story, you know what his famous line is, "No, no, I will not let them go" and Moses keeps asking while God sends plague after plague until the Passover. My precious three year old knows this story very well, it's one of his favorites (his other favorite is David and Goliath).
We were at a friends house the other day and I told Davis to do something, he looks at me with this stern face and says, "No, no.........(what seems like hours later) I will not let them go." This was one of those moments where you sit stunned for a moment--do you rebuke or laugh (because I wanted to do both)? My friends laughed, but I had to reprimand, because I can't allow him to tell me "no" no matter how he does it--even if it's through the voice of Pharaoh.
Later, when I was thinking about the whole event, I realized: man, my kid is really smart! I decided to be thankful for his incredible intelligence and genious creativity instead of being irritated.