In my vision, (possibly after a 20th Century Fox logo is cut into grass by a lawnmower or into a bush by hedge clippers) the film opens with Hank Hill talking to the audience and giving them a list of the profanities listed within the upcoming movie and commenting, "What kind of filth do they put into movies these days?". He then tells the audience that any families in the theater should leave right away if they were good parents. Bobby then walks into the picture shouting and asking if he can see the movie. Hank makes his wierd exasperated noise and then he drags Bobby out of the screen with his hands covering Bobby's eyes.
Since every episode of King of the Hill deals with realistic, daily scenarios in the first place, it makes it harder coming up with a King of the Hill storyline that could be serious enough to be made into a feature-length theatrical movie. I feel it shouldn't be about Luanne having her baby, because that could just be an episode. And if Dale should discover the truth between Nancy and John Redcorn within the movie, I don't know about that either. All I know is that if Cotton hadn't been killed off in the show, he could have added comedy to the movie. I also know that there should be a scene where Luanne's top falls off and she exposes her boobs by accident. Besides that, the movie plot, random scenes, or jokes are all open to anyone to suggest or to add on to my ideas.
One possible plot could be where The Republic of Texas tries to become its own country and a war starts between Texas and the United States, much to Hank's horor. Just kidding!