It's extremely bad for your brain cells and it's also very bad for your heart.
Just think about how it works. You PASS OUT. You basically strangle your brain of all oxygen until you go unconscious. Worst case scenario: you **** up your heart and don't wake up. The pressure on the chest is risky. It's similar to the CPR procedure, only in the reverse. This game is supposed to hold the lungs. However, the problem with this is it could put enough pressure on the heart (or one of it's chambers) to start an irregular beat.
Quite frankly, this would probably rank in the highscore of stupid things I've seen people do.