Sumiko says it's been too long since she's done a self belly punch challenge, so she decides to do one right now! This time, to make the challenge more intense, she also puts her bellybutton to the test by ramming a pencil into her bellybutton until she gives from the pain. Sumiko tests the strength of her abs by delivering hard punches to her flexed and un-flexed abdominals. Ouch!! See how much punishment her abs can take before she decides she can't continue.