Sandra tells Alex to lick her dirty street boots. First slave licks top surface of her black leather boots. Then Sandra tells him to lick disgusting soles of her boots. Alex licks and swallows all dirt and mud from Sandra's boots. Mud are really nasty, because it's comes from crowded subway, public buses and dirty streets of megapolis. So a lot of germs and other disgusting stuff was licked and sucked by Alex today.