It's simple. Priest Maxi didn't want there to be a Halloween, so...
Jonathan: It's simple. Priest Maxi didn't want there to be a Halloween, so he decided to scare everyone away from the docks.
David: Yeah. And then he used this flashlight and some cotton swabs to create the ghosts. (shows the flashlight and swabs, then shines the light through the swabs. The pirate ghosts appear in the distance)
Fieldy: (with some cheese and a cup)Then all he needed was some sound effects created by this cup and a piece of cheese. (holds them to his mouth and sounds) Aaaaraargh!
Jonathan: And all he had to do then was create a ghost ship, by using some candles, a mirror, and two squirrels. (genuflects to place the candle between the mirror and the squirrels. A pirate ship appears on the lake)
Chef: Father, why did you go to all this trouble?
Fr. Maxi: Because Halloween is an abomination of God. I would do anything to stop this wretched, unholy holiday!
Chef: Including killing people and wreaking havoc all over South Park?
Brunet: Don't you see that by trying to stop Halloween you've scared the hell out of everybody?
Fr. Maxi: No.