It reads as if Benjamin got just what he needed. Its that natural reaction of their body when we give a proper spanking to a bare bottom and we have to see that and hear them.
There is also side to side movement of Shauns hips he will be trying to twist his hips and his shoulders in reaction to the horrible sting of my brush, when the spanking starts he straightens his body, flexing, clenching his bottom cheeks and relaxing them and when relaxed there is plenty of "jiggling and bouncing of his bottom not hips his bottom and he will be flexing it hard as well from that overwhelming burning pain from my brush, he goes back and forth between draped and arching his back and legs as he wiggles, he tries to twist when the sting of the brush gets to be too much and kicks away but I have his right arm held firm against his back.