1.Grease started off as a musical in 1971. It was created by an advertising copywriter named Jim Jacobs and a high school art teacher named Warren Casey. It was adapted into a film in 1978.
2.The title, Grease, was a way for the creators to pay homage to the 1950s and the era's "greasy hair, greasy engines, and greasy food."
3.Happy Days star Henry Winkler was originally offered the role of Danny Zuko, but he turned it down out of fear of being typecast.
4.Randal Kleiser, the film's director, had several people in mind for the role of Sandy Olsson including Carrie Fisher, Susan Dey, Deborah Raffin, and Marie Osmond. Marie was the frontrunner until she objected to Sandy's "good girl to bad girl" transformation.
5.Elvis Presley was initially offered the role of Teen Angel, but it was ultimately given to Frankie Avalon.
6.The song "Beauty School Dropout" got its name after the writers for Grease saw a news report about a teenager who dropped out of beauty school and became a murderer.
7.For the movie, a lyric from "Look at Me, I'm Sandra Dee" was changed to something a little more sexual: "Elvis, Elvis, let me be! Keep that pelvis far from me!" Coincidentally, Elvis Presley died the same day the scene was filmed, August 16, 1977.
8.While filming, everyone in the primary cast was actually too old to be in high school. Director Randal Kleiser administered a "crow's-feet test" around their eyes to make sure they could pass for teens.
9.Lucille Ball's daughter Lucie Arnaz was originally up for the role of Rizzo, but was later dropped from consideration after her mom told producers this: “I used to own that studio; my daughter’s not doing a screen test!”
10.Instead of using makeup, Jeff Conaway (Kenickie) insisted on really giving Stockard Channing (Rizzo) real hickeys and he did! Remember, "A hickey from Kenickie is like a Hallmark card."
11.Dina Manoff (Marty) was not a good dancer at all, so they made sure to exclude her character from all of the dance numbers.
12."Greased Lightning" was originally supposed to be Jeff Conaway's (Kenickie) song, like it is in the musical, but John Travolta (Danny) insisted he sing it. This caused a bit of tension on set.
13.Jeff Conaway (Kenickie) injured his back while filming "Greased Lightning." Fellow cast members accidentally dropped him while dancing on top of a car. The injury eventually ignited his pain killer addiction, which led to his untimely death in 2011.
14.The scene where John Travolta (Danny) pulls out Saran wrap during the "Greased Lightning" number is actually a sexual reference to condoms.
15.The "Sandy" number would've ended differently if it were up to John Travolta (Danny). Instead of the hot dog jumping in the bun, Travolta wanted a close-up.
16.Production was halted during the drag-racing scene, due to cast members becoming mildly ill due to the filthy water in the LA River. Director Randal Kleiser even caught a foot infection because of it.
17.John Travolta (Danny) was still grieving the loss of his love Diana Hyland, who died from breast cancer in his arms. He called the film director at all hours of the night to talk.
18.Olivia Newton-John was extremely hesitant about making her transition from "good girl" Sandy to "leather and Spandex" wearing Sandy. John Travolta (Danny) actually had to talk her into it.
19.Speaking of Spandex, Olivia Newton-John's pants were so tight when filming "You're the One That I Want," that she had to be ripped out of them and sewn into them.
20.It actually only took one day to film "You're the One That I Want" and the end scene. There was also a real traveling circus there.
21.And the iconic dance contest took an entire week to film. It was shot in Huntington Park High School in Los Angeles. Temperatures reached a scorching 116 degrees during filming, which caused several extras to get mildly ill.
22.Porn star Harry Reems was originally considered for the role of Coach Calhoun, but producers thought it might hurt the film's success. They ultimately replaced hime with Sid Caesar.
23.Jeff Conaway (Kenickie) had a big crush on Olivia Newton-John (Sandy) and was really nervous around her on set. Oddly enough, he ended up marrying her sister, Rona Newton-John.
24.In the original stage production of the show, Sandy's last name was actually Dumbrowski and was of Polish-American decent. They eventually decided to change it for the film to match her Australian background.
25."Hopelessly Devoted to You" was written AFTER they finished filming the movie. Olivia Newton-John's ballad was the only Grease song nominated for a 1979 Oscar. It was up for Best Original Song but lost to Donna Summer's "Last Dance."
26.Annette Charles (Cha Cha DiGregorio) suffered an ectopic pregnancy while filming Grease. After filming the drag-racing scene, she was rushed to the hospital for emergency surgery.
27.Coca-Cola initially had a product-placement deal with the film producers, but after negotiations went south, they were forced to obscure all references to the beverage in post-production.
28.Believe it or not, the word "grease" is never said in the film, only "greased."
29.John Travolta's sister, Ellen Travolta, plays a diner waitress in the film. She had one line: "Oh, there’s Danny and Sandy,” which was said while watching the dance contest on TV.
30.Rydell High takes place at three different LA high schools. The building's exterior is Venice High School, the interior is Huntington Park High School, and the field is John Marshall High School.
31.John Travolta (Danny) kept messing up a line so much, they decided to just keep it in the movie. He says "heap lap trials" instead of "heat lap trials."
32.One of the original adaptation ideas was to make Grease an animated movie. It ultimately became a live-action film, so they decided to just make the opening credits animated instead.
33.Grease became the highest grossing film in 1978. Its soundtrack was the second best–selling album of the year, behind Saturday Night Fever, which also starred John Travolta.