Well, you don't really want to get in more trouble right now, and singing doesn't seem like a bad thing, so you join in a rousing chant of, "Satan, Satan, Satan..."
"Hey, buddy," the pale kid sings to you, "we're having a cook-out slash goat sacrifice tonight. You wanna come and get baptized in the unholy flames of the dark one's rage?"
"Sure," you sing back.
The two of you leave detention together a little bit later, heading directly to the festivities. It turns out, they were just waiting on you to sacrifice the goat.
"Would you like to do the honor?" somebody sings at you, holding out a curved knife.