It's a big hole formed around your backside, underneath the skin, that can infect and it becomes VERY VERY painful. You can't run, you can't lie on your back...
I thought I'd share this with you guys so you can start exercising a bit more for those who don't, and try to avoid the "rough" sports like snowboarding and karting which affect the specific area, because that is where I got mine from. When you do stand up from the chair after hours of not moving, DON'T stand up IMMEDIATELY. You'll stretch the soft tissue and this forms holes inside!
Most of the times, it will require surgery. And 40% of those having surgery will have it at least once more.
Did anyone here have it?