paingasm
The worst pain you feel just before your muscles let go, like when you've been doing push-ups for an hour and your arms are about to quit.
My legs felt like they were on fire right before I collapsed from a paingasm.
She twisted my arm so hard the pain hit me like a paingasm just before it snapped.
He ran a marathon and got a paingasm in his legs that made him scream like a girl.