One of my friends owns a toy company that makes Max's favorite toy. It's the Wheel Tweet Small towards the bottom of this page. While doing some spring cleaning, I found one that I hadn't yet given to any of the parrots! (It's also a favorite of Rocky and Calypso).
Max was so happy and proceeded to play with this for quite a long time, which allowed me to get more cleaning done as I wasn't having to remove a curious grey to a more appropriate place.
I decided to take a video of it to share with my friend, but then Stella's reaction led to me posting this on the blog instead.
I think Stella was making this noise to show her displeasure that Max was getting all of the attention. After turning off the camera, I gave her a toy of her own and she busied herself destroying it.