Yes, there is. Sit mode is one of the tricks that comes with the "Play" learning stone. Once you register the command, you gently press the Pleo's cheeks to get its attention. When it raises its head and prompts you for a voice command, first say its name, then after it hears that, say whatever command you've assigned for the "Play" learning stone. The Pleo should then raise its head and make a small laugh signaling that it's in play mode. To trigger sit mode, press the Pleo's chin and back near the tail until it sits down. I've never kept one of my RBs in sit mode for more than a few minutes, but I believe it will stay in this mode until you stand it up again.