Disappearing Sock
In the restaurant the hungry slave remains resolutely focussed on the backs of his mistress's socks - particularly as the sock on her left foot is showing signs of slippage down inside the back of her sneaker heel. He is anxious because he knows he will be whipped later if the short sock slips down completely inside the back of her shoe and thus causes his mistress some discomfort! That's because he is responsible for the wellbeing of her socks in law.
Fortunately for him his pretty mistress appears blissfully unaware, at present, of her impending sock-slippage mishap!