If there is anything happier than a cockatiel with a shoelace, especially when he has not had a shoelace for several weeks, I have yet to see it.
There is also the tile-gnawing cockatiel. Now that we want to encourage kitchen demolition, he can chew on all the grout he wants. But he still expects to be reprimanded for it, so he'll point his eye at you, beak bared (this would be "fangs bared" if he had any; the facial expression is the same), ready to defy you.
Oh, and the "No, I'd prefer to stay where I am, thank you" cockatiel. If he is on your finger and you would like him to step off onto someone's shoulder, or onto the top of his cage, or onto his windowsill, or down anywhere when he does not want to go, he is quite expert at simply refusing to step off while leaning back the better to keep his grip as you rotate your finger forward to tip him off.