I get bell ringers consistently by following the advice in the megathread on this forum. The only way I can describe it is that it feels the way I imagine a female orgasm does. It is overwhelming, overpowering, and incomprehensibly good.
with that said, in seeking bell ringers, I have also come pretty god damned close to a heart attack several times. To me, a bell ringer is getting close to actually damaging yourself without actually doing it. Once, I took three gigantic rips in a row and my heart sped up until there were no beats, just a constant hum....until it started slowing down. And when it got down to one beat every two seconds, I went blind. I lost all control of my body and absolutely believed I was dying. Managed to pull myself up and breathe lamaze style while punching myself in the chest then sprinting down the stteet. After a while, I was okay again. But this is what you risk, in my opinion, by seeking out such violent highs as the bell ringers that make up the most ecstatic experience I have ever had on drugs.