Despite the study referenced in my last post, I'm guessing the people participating in this ritual did not have high levels of oxytocin, at least during the ritual itself. Having nails driven through your hands is a pretty horrifying way of "celebrating" Christ's crucifixion. This is definitely Extreme Religion:
Devotees in villages in the northern Philippines took part in a bloody annual ritual to mark Good Friday...The crucified devotees spent several minutes nailed to crosses in Pampanga province while thousands of tourists watched and took photos of the spectacle, which the church discourages. Earlier in the day, hooded male penitents trudged through the province's villages under the blazing sun while flagellating their bleeding backs with makeshift whips. Others carried wooden crosses to dramatize Christ's sacrifice.