In the world of body modification -- body inflation, as it's called -- is not a new phenomenon. Modern primitives have routinely injected saline into different parts of their bodies. Usually the abdomen, occasionally, the testicles. Don't ask.
It never ceases to amaze me the lengths modern primitives will go to push the envelope. It is what both fascinates and disgusts me about it. On one hand, you find yourself amazed at the dedication these folks have, but on the other, it seems they are quickly on their way to sucking the joy out of every last experience in their life.
Forget about sexual predilections where you start with a little harmless spanking, then wake up five years later having to be hoisted up on hooks while you masturbate in order to get off. This is my inherent fear with body modification and fetish, in general. There does not appear to be a road back.
Thankfully, in the case of body inflation, specifically "bagel heading," your body will absorb the saline in about twenty-four hours. I guess that's good. You can get your freak on and the next day at work, nobody will be the wiser.