"Two Guys Naked in a Hot Tub" pokes fun at two notable cult-related incidents in the U.S. from the 1990s: the 1993 Waco siege and the 1997 Heaven's Gate mass suicide.
Stan is upset that he has to go and becomes even more angered when he is locked in a room with nerdy "Melvin" classmates that he does not like: Pip, Butters, and Dougie.
Determined to prevent this, they set up a blockade and prepare to open fire on the cult if they do not desist; at one point, a couple of party-goers leave and are immediately fatally shot (due to the ATF believing they had weapons despite them clearly not having any).
The kids record a video tape showing that the party inside is not a cult to the Newsman; the ATF realizes their mistake, claiming it was a "test simulation" and quickly disperse after their secret weapon, a large rocket called "The Negotiator", fires and destroys every home in the neighborhood except for Mackey's.
The credits roll with a parody version of Cher's "Believe" (which the ATF used to drown out the party-goers in an effort for them to submit, unaware that Mackey was playing the same song and which everyone enjoyed).