Jesus vs. Frosty begins with four boys building a snowman and, in the vein of Frosty the Snowman, putting a magic hat on it to make it come to life. Unfortunately, Frosty turns out to be evil and deranged, sprouting huge tentacles and killing Kenny (who resembles Cartman from the South Park series) by throwing him. This leads one of the boys to utter the first version of a line which recurs in countless South Park episodes: "Oh my God! Frosty killed Kenny!" The boys go to Santa Claus for help, but he turns out merely to be Frosty in disguise. This time he kills the unnamed boy, who resembles Kenny from South Park, again by throwing him. The two remaining boys run away, and come across a nativity scene with a baby Jesus, who flies over to the evil snowman and defeats it by slicing off the magic hat with a hurl of his halo. One of the boys says another recurring line from the South Park series: "You know, I learned something today", and he and his friend realize the purported "true" meaning of Christmas: that is, presents. As a deer nibbles on Kenny's corpse, they go to their homes to find presents hidden by their parents.
In 1992, Parker and Stone made The Spirit of Christmas (aka Jesus vs. Frosty) while they were students at the University of Colorado under the "Avenging Conscience Films" moniker. They animated the film using only construction paper, glue and a very old 8 mm film camera, and premiered it at the December 1992 student film screening. The film features four children very similar in appearance to three of the four main characters of South Park, including a character resembling Eric Cartman but called "Kenny", a hooded boy resembling Kenny McCormick (who remains unnamed) and two other boys similar in appearance and voice to Stan Marsh and Kyle Broflovski.
This film is later referenced in a season six South Park episode entitled "Simpsons Already Did It". In this episode, Stan, Kyle, and Tweekare building a snowman, and Tweek is reluctant to put the nose on the snowman and says that this is because he thinks it will come to life and kill him, to which Stan replies, "Dude, when has that ever happened except for that one time?"