"Push (Feelin' Good on a Wednesday)" (aka "Ya ya ya, I am Lorde"). Has a catchy beat, sounds like an authentic Lorde song, and the song actually sounds like a call for acceptance of who one is and a defiance of others' disapproval.
The Circle of Poo. It sounds like some joke parody of "Circle of Life", but it sounds so fucking glorious. Especially Cornwallis' singing voice near the end.
Wendy's naughtier version of the Miss Susie song. This marked the first time they were able to use "shit" and "cunt" uncensored.
"Queef Free", where all the males in South Park feel remorse for being disgusted by women queefing yet finding men farting funny, and to show the women their remorse, sing the awesome message that it's OK for women to queef.
"Boogers and Cum" became an instant hit overnight and gained a hashtag on Twitter in mere minutes.
From the same episode, "Give Life a Try." A surprisingly catchy rap song in the style of Logic in which Cartman raps about wanting to kill himself because he thinks his girlfriend Heidi is abusive.
From "Hummels & Heroin" we have "Locked Up In Here", an aggressive trap/hardcore rap song featuring Atlanta rapper Killer Mike, talking about everyday life in a retirement house and comparing it to a straight-up prison.
The Movie counts on its own because it is not only a musical, but a 90 minute or so work of art. This isn't the entire soundtrack, but is enough to realize the movie's awesomeness.
"Little Mountain Town" is a good introduction to the show, especially for anyone who hasn't seen South Park before the movie. The viewer is introduced to the main cast, and are roughly presented with the plot as the boys have to resort to using a homeless guy in order to secure tickets to their movie.
"Uncle Fucka". Not only are we introduced to Terrance and Phillip, we get a awesome fart solo that contributes to Kenny's death and leads to him going to hell.
"Up There", sung by Satan, tells of his desire to live where babies burp and flowers bloom. The ending is badass awesome: "IF ONLY I CAN LIVE UP THEEEEEEEEEERRRRRRRREEEEEEEEE!!!!! I WANNA LIVE, I WANNA LIVE UP WHOOOOOOOOO!!!!!!!"
"I Can Change". Saddam Hussein sings this song, at least the South Park version. We are told that he is in hell because Saddam was killed by a pack of wild boars. Why is he saying that he can change? It is because Saddam comes off as wanting a homosexual relationship with Satan while Satan is non-committal about their relationship.
"Kyle's Mom's a Bitch". Despite appearing in the Season 1 episode "Mr. Hankey, the Christmas Poo," the movie version is an "over the top" hilarious number for Eric Cartman. Cartman sings the song while doing a little jug which includes examples from all across the world. But the Over the Top Finale is a top notch showstopper complete with an Oh, Crap! moment.
"What Would Brian Boitano Do?", The kids sing the song in order to provide inspiration to save Terrance and Phillip.
"What do you do when the world is in trouble? If you are the boys of South Park, you form a group to rescue your heroes, and "La Resistance" is the battle song. Seriously though, this song is important because the entire world is against the boys. At this point in the movie, the parents have managed to convince the US Government to go to war against Canada, but mob rule is in effect as Terrance and Phillip are scheduled to be put to death during a USO Show. Finally, we find out that when Terrance and Phillip die, Satan will rise.
"Blame Canada". Like "La Resistance" this song is also a battle song, but sung by the adults of South Park as reasoning to blame somebody else instead of their own shortcomings that allowed the kids to view the movie in the first place. Here is the Oscar performance.