Master has tied the slave up and uses his face as a footrest. The slave must sniff every part of Master's sweaty gym socks and suck the sweat out of them, while the Master is laughing at him and humiliating him verbally. The slave complains that Master's socks are too stinky, but the Master doesn't care and continues using his face as a foot toy, wiping the sweat and stink into it.
Two angles - full view and a close-up of the sniffing action.

Master has tied the slave up and uses his face as a footrest. The slave must sniff every part of Master's sweaty gym socks and suck the sweat out of them, while the Master is laughing at him and humiliating him verbally. The slave complains that Master's socks are too stinky, but the Master doesn't care and continues using his face as a foot toy, wiping the sweat and stink into it.
Two angles - full view and a close-up of the sniffing action.