In the sleep mode, go to the toy area to the right of the spawn point (in the big spacious room, opposite corner to the doll house), there's a blinking traffic light there. In front of it there's a big carpet that starts with a green stripe (starting line) and ends with a red stripe (finish line). Stand on the green edge of that carpet and the traffic light turns green, starting the game. The goal is to reach the red stripe but you're only allowed to move while the light is green.
The thing is though, nothing happens whether you win or lose. The minigame is just... there.