Now that’s intense.
Update: Since people are asking, the “why” answer is because the navel is very sensitive and many people greatly enjoy this type of navel play (BME/HARD has a lot of navel play pictures). The “how” answer is because it’s a skewer, not a beveled needle, so when it pierces tissue it spreads more than cutting, and pushes things out of the way before penetrating them. If you want to find more information on this in a fakir context, try a search for “Mirin Dajo”.
PLEASE DO NOT TRY THIS UNLESS YOU KNOW WHAT YOU’RE DOING!!!