Here in my hubby's hometown, Catholics have a yearly ritual which is part of their devotion to their Creator during Holy Week. It is also yearly that I get to witness their Holy Week devotion.
Men whip their backs in flagellation until their skin bleed. They will walk like 2 kilometers on the streets carrying a cross made of woods and some also walk with a crown of thorns on their heads.
Although, all of their faces were covered, I think people around can still recognize them since this is just a small barrio and almost everyone knew each other.
When they finally reach their local church, there they will pray and plead. You will see men who will continously whip their backs.
What they do is obviously painful. It's pretty sure each of them has their own best reasons of doing this. I am no longer a Catholic but I have nothing against their beliefs and traditions.