What about that marble trick?

Saw my PS yesterday, 7 weeks PO.  He said everything looked really good, but that he didn't want my BB to shrink anymore.  He told me to tape a marble into my belly button.  I'd read about it, but until he asked me to do it I was quite skeptical.  Anyway, found and boiled a marble.  Before bed I tried to put it in place, but it was too big.  I must have gotten a bit enthusiastic, because I pushed it in hard and next thing I know, it's stuck and my BB is bleeding!  I couldn't remove it, so freaked out a bit.  I covered it with gauze and tape and went to bed.  By morning it was working its way out and I was able to remove it.  I'm not too excited to try that again, and I read that people also use ear plugs, which sounds easier.  What are your experiences and any suggestions?