Here’s a classic trick that never gets old: Play dead. Use a clicker to shape this behavior. The click should come right at the moment when the dog has completed the task. Early on, you might click just for him lying down and then for flopping over onto his side a bit. With a dog that’s had some clicker training before and knows that he’s got to offer a behavior to get the click, this should go quickly. You can teach a roll-over the same way.