Aren't they so funny. Usually it's the alpha female that does this. My darling Sammie has a certain stuffed animal,we named it Humper, that she just goes to town on. At times, she take it in her mouth, give it a good hard shake w/ a growl,as if to say she is not getting her satisfaction.LOL.
Sometimes she'll finish w/ it & lay there panting. I've even asked her if she wants a cigarette.LOL