There were very few other people at the zoo when I visited, and I had the two large cats to myself.
The cougar was pacing furiously as I approached and was further agitated by a zoo truck that drove by.
I purred. Loudly.
It took notice, looked at me and eased its pacing. Fairly soon, in two elegant leaps, it got upon its highest shelf, lay down and, acting like other kitties, rubbed its head on the shelf, softened its eyes, relaxed and took cat naps. It is not asleep here, just enjoying being purred at! It was several minutes of magic.