Surprisingly hard hand trampling with Birkenstocks

Description: The slave was really relieved when he saw that i'm not wearing high heels for his daily hand trampling training, but only my birkenstocks. but he clearly underestimated how much these shoes will hurt him. while they're very comfortable for my feet - the sole's bottom is rock-hard and has a distinct tread ... which will not only hurt him immensely, but also leave behind nice marks all over his fingers and hands. obviously, i also know very well what to do, to make them hurt even more! he's struggling to cope with the pain as i stand on a single hand with my full weight and stomp down on his hands ... he definitely needs to toughen up! his pain tolerance is way too low to come anywhere close to my expectations ... and therefore we'll spend some more time training him!