In modern times, it has been speculated that the more extreme practices of mortification of the flesh may have been used to obtain altered states of consciousness for the goal of experiencing religious experiences or visions; medical research has shown that great pain releases endorphines which can have such effect, and even get some fethishists addicted to pain.
During the neighborhood processions, several flagellanti ("flagellants") join in. They gently strike their backs with a metal scourge. On the Sunday procession is joined by several hundred battenti ("beaters") who strike their chests with a spugna (literally "sponge," it is really a disk of cork holding dozens of pins). Designated helpers pour white wine on the sponges during the procession, supposedly to ward off infection. There are a few dozen flagellanti during the Sunday procession, who also provide crowd control. The flagellanti and battenti are anonymous. They wear white hoods and are not even supposed to tell family members they are participating. Scourges and sponges are not carried openly or displayed in homes after the rite. The battenti are all men, although a few of the flagellanti are women.
Additionally there are a few dozen symbolic child flagellanti. They wear black robes and caps, and very gently swing a small scourge over their shoulders.
Very similar practices exist in non-christian traditions, including actual flagellation amongst certain branches of Islam (especially Shiites commemorating the murder of Ali), as well as milder traditions such as whipping women (while spanking -discussed there- man) in a Taoist temple on the Chinese New Year.
from MONTY PYTHON & THE HOLY GRAIL
Dingo: You must spank her well, and after you are done with her, you may deal with her as you like... and then... spank me.
All: And me. And me too. And me.
Dingo: Yes. Yes, you must give us all a good spanking.