LOL Bear does that alot. He was participating in a university childhood development study and I just sat there and watched him mess with the poor tester. It was very funny and sad really...

Another time Wolf's grandma was reading him a numbers book (he was maybe 2 at the time), really exagerating the numbers and asking him if he could say them, which number is this, etc... He just patiently humored her, even baby talking the numbers, until the last page that listed all the numbers where he very deliberately looked at them, looked at her and counted very clearly and precisely pointing at each one, 1-2-3-4-5. I had told her through the whole process that he knew his numbers...

I think GT kids really quickly figure out that most people will underestimate their abilities and that they can think and talk circles around a majority of people.