Slave Has To Gobble Our Muddy Boots

Were taking the slave for a walk in the forest. It rained fairly a lot in the past days and the ground is very muddy - quickly our boots are covered in mud. We sit down on a fallen tree and display the slave our dirty boots, but he hesitates - doesnt he know what his job is?! We make him lick all 4 muddy boots clean and in the end his tongue is the only thing left dirty!