You can check out a video of the incident here. It shows the man bringing an iPhone battery up to his face, then biting it, and as he removes the battery from his mouth, it explodes. Taiwan News reported that the customer was at the store buying a replacement battery for his iPhone and that because Chinese electronics stores often carry fake Apple products, the man was probably biting it as a way to test its authenticity.
Apparently nobody was hurt and the video -- CCTV footage posted to Miaopai.com -- is nearing five million views. However, that no one was injured by the blast is probably just a major stroke of luck, so please don't go repeating it just for fun. We don't need battery biting to be the next Tide Pod Challenge.