Oh dear, bad idea. You think you are worthy or worshipping my ass over my feet? You're a slave, so you are to worship the basest part of my body you can, and only if I tell you to worship a better part are you allowed to.
For your presumption it's time for some punishment again.
It will be 20 spanks on each cheek, but after every pair, you will crawl around the room on your hands on knees like the dog you deserve to be. Now continue to page 15 to worship my feet like you should.