As for hurt- it depends on how close you hold it, or how far away... and how high you turn it up.
Electro play can be wild if you know what you're doing. I use and create variations of this lighter version of electro torture for use in my shock box on all ten toes and clips that attach to the soles of the feet. The spark will jump a good distance giving a magnificent show in dim lighting.
If you really want to add some spice to it, get the garland attachment or make one yourself (be sure to leave a gap between garland on metal rod for safety) .. and drag that over her soles..and THEN you'll have quite a show!