flagellation is a form of punishment of whipping and scourging the body. jesus christ had to experience flagellation before his crucifixion and it was very common during medieval times to the middle ages.
in the philippines, self-flagellation is still being practiced during lent despite the strong disapproval of the catholic church. it involves the penitent, after slashing his back with a blade or a knife, scourges himself with a bamboo whip sometimes even with shards of broken glass at each end.
every year during good friday, a province in the philippines becomes a tourist attraction because of flagellants in a parade. such horrid self-inflicted pain is being seen as a kind of penance, but i think it is rather becoming a type of curious entertainment on ogling blood and gore.