Hmmm. Why would you be curious if you do not intend to make them puff up? I think this is the most inhumane way of stressing you puffers. As an owner of more than 10 puffers, I 've never seen any of my puffers doing it. However, they occasionally do puff up in a mild manner, which should be no concern. Puffing up will not kill your puffer instantly, but please do not risk the health of your puffer just for entertainment.