Since South Park might end with a film, I decided to type an idea for it. Please add as many ideas as you can to make this a better movie idea.
It starts with shots of different parts of the South Park world and characters from each part waving (Satan in Hell, Tom Cruise on the Moon etc) to music which I haven't decided on yet. Then the screen will show the South Park sign and it will go to Stan's house. Here, Stan, Kyle and Kenny are watching T.V and the doorbell rings. Stan answers the door and Cartman is there holding seven tickets to the Terrance and Philip LIVE show in Canada. Cartman reveals that he got them off a nice man dressed in black who said that if Cartman bought five tickets, he would get two free. The boys decide to have a contest to decide who comes with them to the show with them. The nominees are Craig, Clyde, Jimmy, Token, Timmy, Tweek and Butters. The boys instantly kick out Butters because they don't think that he's cool, so Butters becomes Professor Chaos in anger . Cartman asks Craig why he should go with them to which he responds 'I saved your f*cking lives in Peru'. The boys eventually decide on Jimmy and Token, enraging the others. Meanwhile a strange man starts following Professor Chaos and eventually grabs him.
Later that day, Craig, Clyde,Timmy and Tweek are stalked by a hooded figure and are all kidapped. Butters then wakes up in a lab and is injected with a strange liquid by a hooded figure.
The boys are then at Terrance and Philip LIVE when another hooded figure walks out on stage behind Terrance and Philip with a gun and threatens to kill them unless he was given everyone from South Park who was in the audience. The boys are handed over to the figure. They are taken to a warehouse where they see every other resident of South Park being kept hostage by hooded figures who then remove their hoods and are revealed to be various villains from throughout all 15 seasons of South Park. They include Mel Gibson, the Cult of Cthulhu, Tom Cruise and his army of celebrities(Cruise was brought back to life by a machine, so he is now half machine), Damien, Saddam Hussein, Scott Tenorman, three Crab People, Steven Jobs, Funnybot, the Guinea Pirate (in human form) and five Mongolians. They reveal their plan to trap everyone in South Park in Imagination-Land as revenge for pissing them all off so many times. Cartman struggles and almosts escapes but, in the process accidentally breaks the Imagination Portal, sucking everybody into it in the room into it!
Butters awakes in a room next-door to the Imagination-Land Portal and realizes that the person keeping him there was sucked into the portal. He searches around town and finds almost no one left so he decides to travel to Washington D.C to find help!
Meanwhile in Imagination-Land, Randy has set up a camp large enough to hold at least 50 people. Altogether in the camp there is Randy, Jimbo, Mr. Garrison, Officer Barbrady, Linda Stotch, Sheila Broflovski, Gerald Broflovski, Sharon Marsh, Liane Cartman, Stephen Stotch, the Mayor, and a few other minor adult characters (everyone except Kenny's parents who are at a poor people fair in Washington). Randy tells everyone that their imaginations are trying to kill their children and that this is their home now and so they must take over and rule Imagination-Land. All the adults agree with him.
Kyle then wakes up in the gumdrop forest and sees Stan unconscious near by. Kyle carries Stan until he discovers another camp made by people from South Park. In this camp however, there is only kids and it is lead by...Cartman. All the boys at the camp are Cartman, Craig, Tweak, Clyde, Token, Jimmy, Timmy, Wendy, Bebe, Red, Stan and Kyle. Cartman then tells everyone that the Jews are the reason that they were sucked into Imagination-Land and everyone turns on Kyle and they decide to beat him up. At that moment, Stan wakes up and defends Kyle and Token, Jimmy and Tweak decide to defend Kyle too. The kids start fighting and Cartman jumps on Kyle, causing the two of them to roll down a hill and accidentally discover a portal out of Imagination-Land! They call all the kids to come down to them, but all the kids are suddenly attacked and most of them are kidnapped by an army of a few hundred Christmas Critters. The kids who escape through the portal are Stan, Kyle, Cartman, Jimmy and Craig.
Butters is about to make the journey to Washington when a portal opens and Stan, Kyle, Jimmy, Craig and Cartman fall out through it. They decide to go with Butters on his crazy journey only Stan has the idea to take a caravan (a house on wheels) to travel quicker. Everyone hops in the caravan and Craig gets behind the wheel.
Meanwhile Randy leads all the adults across Imagination-Land in an attempt to take over Sunshine Castle and rule Imagination-Land. They discover that they have the same powers that the boys did in the episode Imaginationland and they use it to take over Sunshine Castle. As they take over, Scott Tenorman watches it unfold, hidden in the trees.
Kenny and the other children are then taken to the Evil Side of the Imagination where they are handed over to the South Park villains from the start, who are calling themselves the South Park is Evil Revolution Movement (S.P.E.R.M) and plan to take the kids hostage, causing Kenny to try and run away and get attacked and eaten by Alien. Kenny then wakes up in his bed, which is just outside the Pentagon as his parents went to a poor people fair and brought Kenny's bed to use during the night.
The boys are traveling across America and Cartman drives the van with everyone in it off the path to Washington D.C to go to Kentucky and get a bunch of K.F.C. The other boys awake after he arrives and are furious with him for going off the path but Cartman blames it on Butters, who is then beaten up by everyone. Butters is then thrown out of the van and is sent rolling down a hill. The boys then realize that Cartman did it and they try to throw him out as well but he struggles and everyone falls out while the van is still moving and they all tumble down the hill after Butters.
On the Evil Side of Imagination-Land, Wendy asks Saddam Hussein what S.P.E.R.M's plan is to which he replies bad things, very bad things. Wendy is then taken to a holding cell with all her classmates and she whispers to them that they need to escape. Token comes up with a plan to escape and whispers it to the others.
Kenny then sneaks into the Pentagon, smashing the same window that Kyle and Cartman smashed in Imaginationland. The American government doesn't believe his story about Imagination-Land and he is kicked out of the Pentagon. He the decides to call Satan in Hell, who gave Kenny his phone number last time Kenny visited and informs him that Saddam Hussein is involved with the plan. Satan agrees to help.
Randy and the other adults are walking around Sunshine Castle as they trapped all the good imaginary characters in the basement, when Randy sees an army of evil Imaginary characters approaching. The adults take out all of the good imaginary weapons that they stole from the good imaginary characters, and they attempt to defend the castle. Then five minutes later half the adults are dead and the other half have been kidnapped by Evil Imaginary characters, who have taken over the good Imagination-Land with all the good characters still locked in the basement. The Evil characters then hand them over to S.P.E.R.M who they are working for.
Butters then wakes up and sees all the other boys still unconscious after rolling down the hill. Angry at them, he walks off towards Washington D.C without them. The boys then wake up after Butters has left and they head towards Washington D.C only with one problem. Butters took the map leading them to D.C. The boys decide to attempt to travel to Washington on foot with no map.
Meanwhile, all the adults in South Park are forced to dress up as pigs by S.P.E.R.M and are being forced to do the chicken dance while chained to the ground, in front of Oprah (who is apparently imaginary) much to their humiliation. The imprisoned kids then run out in front of the adults, free them and run. Only a number of adults escape and all the kids discover an exit out of Imagination-Land and they run through it, only to find themselves in a prison that resembles a concentration camp.
The boys then are heading towards Washington when they find Butters and beat him up. Butters then apologizes and joins the boys. The group then come across Al Gore, who informs them that he has started an anti-ManBearPig club. The members of the group include Seth McFarlane (the writer of Family Guy), Charlie Sheen and Steven Moffat (writer of shows such as Doctor Who and Sherlock). As Moffat is British, nobody understands his accent and he really annoys everybody by constantly talking. Al Gore then guilts Stan into joining and he is told to sign a contract to join the club. As the boys prepare to leave Stan is informed that he is forbidden from going anywhere without permission from the club because he signed the contract by Moffat. Stan then runs and the other boys follow him. Later that day Cartman discovers another K.F.C and convinces everyone to go to it. Cartman is then convinced by the workers to stay at K.F.C forever and he accepts. The boys then leave without him and Cartman discovers that it is a trap set by Scott Tenorman. He is grabbed by Scotts guards and is taken to Imagination-Land. That night, Stan is kidnapped by The anti ManBearPig club and he is taken to Imagination-Land by Moffat, who works with S.P.E.R.M because South Park think he is too crappy to make fun of.
Stan and Cartman then awake in the same place as all the other kids ended up. In a concentration camp in Imagination-Land! Stan finds Wendy barely conscience from lack of food. Cartman then gives Wendy some K.F.C shocking everyone. Wendy then secretly gets a crush on Cartman again only this time it is much stronger than before.
I will continue updating this whenever I can.