My mom had a dog that would play dead when told to. But he'd be on his back looking at you. Mom would say "Dead dogs close their eyes." and the darn dog would close his eyes! We got him at the pound. The previous owners gave him up because they said he was untrainable. That was they most trainable dog I'd ever seen. Sit, shake hands, other paw, sit up, lie down, roll over, roll over the other way, play dead, close your eyes, hold up 1 finger and he'd bark once. 2 fingers twice. 3 fingers three times. 4 fingers and he'd just start barking and not stop. Jump through hoops, climb ladders, walked on a leash really well, never pulled. The paper boy would whistle at the end of the driveway and he'd run down there, get the paper, and take it to whichever person you told him to. Mom taught him if he came in with wet feet, she'd say wet feet and he'd plop down and put all 4 feet up in the air. She'd wipe off his feet with a rag from a basket by the door, then hand him the rag and tell him to put it away. He'd take it to the laundry room and drop it on the floor in front of the washing machine, then head to the kitchen for his reward. If you'd point as someone and snap your fingers he'd start snarling, bare his teeth and growl and all the hair on his back would stand up. You'd tell him good boy and he'd just turn it off and start wagging his tail. That was scary, actually.
All in all, it was absolutely the smartest, easiest to teach dog I've ever known. My mom taught him all that stuff. And he picked her. She was walking through the pound, all the dogs were going nuts, but he just sat at the cage door and put his paw on her leg as she stopped to look at him, and that was that.
I've seen a few dogs on TV that were like that, but never met one in person. Truly a once in a lifetime dog experience.