Napoleon Dynamite

Preston High School was one of the filming locations for the movie.
Napoleon Dynamite is a socially awkward 16-year-old boy from Preston, Idaho, who lives with his older brother, Kiplin Ronald "Kip" Dynamite, and their grandmother. Kip, 32, is unemployed and boasts of spending hours in Internet chat rooms with "babes" and aspiring to be a cage fighter; their grandmother leads a secret life involving mysterious boyfriends and quad-biking in the desert. Napoleon daydreams his way through school, doodling ligers and fantasy creatures, and reluctantly deals with the various bullies who torment him, particularly the obnoxious sports jock, Don. Napoleon likes to make up stories about himself whilst having a sullen and aloof attitude.
Napoleon's grandmother breaks her coccyx in a quad-bike accident and asks their Uncle Rico to look after the boys while she recovers. Rico, a middle-aged and flirtatious former athlete who lives in a campervan, treats Napoleon like a child. He uses the visiting opportunity to team up with Kip in a get-rich-quick scheme to sell numerous items door-to-door. Kip wants money to visit his Internet girlfriend LaFawnduh, while Rico believes riches will help him get over his failed dreams of NFL stardom and the loss of his girlfriend.
Napoleon becomes friends with two students at his school: Deb, a shy girl who runs various small businesses to raise money for college; and Pedro, a bold yet calm transfer student from Juarez, Mexico. A friendship soon develops between the three outcasts. During this time, preparations begin for the high school dance. Pedro asks Deb to be his dance partner, which she accepts, while Napoleon chooses and attempts to persuade a reluctant classmate called Trisha to be his own date. Inspired by an election poster at the dance, Pedro decides to run for class president, pitting him against Summer Wheatley, a popular and snobby girl at the school. The two factions put up flyers and give out accessories to the students to attract voters. Kip, meanwhile, is head-over-heels in love since LaFawnduh has come to visit him from Detroit. She gives Kip an urban makeover, outfitting him in hip-hop regalia.
Rico's ongoing scheme causes friction with Napoleon when Rico begins spreading embarrassing rumors about him, to evoke sympathy from his prospective customers. Rico later tries to sell Deb a breast-enhancement product, claiming it was Napoleon's suggestion, which causes her to break off their friendship. His scheme ends when he visits the wife of the town's martial arts instructor, Rex, to try and sell her the breast enhancements, but Rex walks in and beats him up after witnessing Rico's demonstration.
On the day of the class president elections, Summer gives a speech before the student body, and then presents a dance skit with a school club. Pedro and Napoleon then discover that a skit was also required from them, and a despondent Pedro gives an unimpressive speech. Napoleon then gives the sound engineer a music tape given to him by LaFawnduh, and performs an elaborate dance routine to "Canned Heat" by Jamiroquai. Summer and her boyfriend, Don, are unimpressed, but the routine receives a standing ovation from all the other students.
The film concludes with Pedro becoming the class president, LaFawnduh leaving with Kip on a bus for Michigan, Rico reuniting with his estranged girlfriend, Grandma returning from the hospital, and Napoleon and Deb making up and playing tetherball.
In a post-credits scene, Kip and LaFawnduh are married in an outdoor ceremony in Preston. Napoleon, absent for the vows, arrives riding a horse, claiming that it is a "wild honeymoon stallion" that he has tamed himself. Kip flicks LaFawnduh's garter as a "keepsake" towards Napoleon, Rico, and Pedro, before he and LaFawnduh ride off across the fields.

Question: How does Napoleon's grandmother break her coccyx?
Answer: quad-bike accident