Arav can just keep on opening and closing the same cardboard box hundreds of times and still not get tired. But he gets frustrated if the box does not open quick enough. He wails out his frustration everytime the flap gets stuck. When we decided to let him be, he simply wailed, waited for our reaction, seeing none, continued to prod and voila the box opened out.

After that the box was history and he moved on to something else.