Sally was very good at flicking her hand, as seen in the photo, waiting for some unruly patron to toss a peanut, or other forbidden morsel of food. Although the zoo has always had a policy of do not feed. I believe one of the first major U.S. zoos to enforce that rule.
I actually won a photo contest with this shot. It was published in my job's monthly magazine. The category was probably for humor. I still have that over 30 year old magazine somewhere in the recesses of my garage.