Another thing you can do:
All the girls and women would react or maybe even do things to the balls, if you record their reaction with a hidden mini-cam. You can get mini-cams on e-bay, they are very cheap. This is what I would try if I had access to balls. I would choose a somewhat quiet location or path where I know girls and women would walk by. I would make it like someone threw away a package of balls on the ground and the balls are already out of the package on the ground. There must be a package next to the balls because of the label because I think most girls wouldn't know it's testicles.
Females like to pretend they are saints, but you would be surprised about what they do when they think no one is watching, and they get more wild when in groups, HAHAHA!