Sex is definitely used often to give a movie some "umph." It can make a really bad movie a little less bad. It's not always neccessary, but it does definitely sell well. Ever since there was film, there were naked people and/or sex in film. Many directors self-censor if they don't agree with nudity. Actors and actresses choose whether or not they want to show more skin than normal. Nudity is not always connected to sex and/or leading to sex.
The 1894 film Carmencita, featured the first woman to appear in front of an Edison camera. The 21-second film was directed and produced by Edison's employee, William K.L. Dickson. The 1896 film Fatima's Coochie-Coochie Dance was the first film to ever be censored. The film features a gyrating belly dancer, and it was censored because of her gyrating pelvis. In 1897, French filmmaker George Melies directed a short film that contained some of the first nude scenes ever recorded. In the movie, a person is seen undressing with the help of a maid. America's first feature-length sex movie was called Traffic in Souls (1913). The 1914 film Damaged Goods, was one of the first education films; it covered venereal disease. The highly controversial film the Birth of a Nation was released in 1915.
This content could be disturbing. Read at your own risk.
15 Teeth (2007)
This is one of the few on this list that is actually on Netflix streaming. It follows a girl who grew up next to a power plant and has developed an anatomical "quirk." She has a set of teeth in her vagina. The doctor calls it "vagina dentata." The main character, Dawn, is one of the girls in high school that speaks to everyone about abstinence and takes the abstinence pledge. But, when a guy tries to rape her, the "teeth" cuts off his male member. They actually show the boy's member on the ground. The teeth also bit off the fingers of a doctor that was trying to molest her during an examination.
14 Re-animator (1985)
Here in this campy 80's horror movie, a couple gets into an experiment to reanimate corpses. It is based on an H.P. Lovecraft short story titled "Herbert West - the Re animator." The scientist had just come back from a trip to Austria and had studied reanimating corpses under a scientist that had just died mysteriously. He enrolls in Miskatonic University and takes up the experiments with his roommate. The film does not really follow the story very well. The original story was meant to be a parody of Frankenstein. The gross scene involves the woman in the picture receiving oral pleasure...from the severed head that is also on the table.
13 Eurotrip (2004)
Eurotrip was definitely a cheesy teenager comedy along the lines of Road Trip. It followed a group of teenagers who take a trip around Europe. Scotty, the main character, gets dumped by his cheating girlfriend on graduation day (which includes a cameo with a singing Matt Damon).
The purpose of the trip was to find the main character's pen pal in Germany. Along the way they make stops in other countries before ending up in Germany. One of the kinky scenes in the movie involves one of the male members of the group finding his way toward a sex shop in Amsterdam and ends up having some VERY kinky intercourse because he can't pronounce the safe word they give him. They tie him up and do weird things with machinery. There was also a scene with Scotty and his German pen pal girlfriend doing it in a church confessional. It may not be super kinky, but is blasphemous.
12 Eyes Wide Shut (1999)
Here we have the Stanley Kubrick classic Eyes Wide Shut. It follows Tom Cruise and Nicole Kidman as a married couple that is trying to spice up their sex life. He sets out to have a night of sexual adventure. He meets a former friend who tells him about some crazy sex parties which involved playing the piano with a blindfold. Tom Cruise's character, William Hartford, ends up at one of these parties, which is basically an orgy. The men at the party all wear masks and robes. The women are all young and beautiful and scantily clothed. Both of the actors signed open-ended contracts. Basically, they committed themselves to Kubrick's project no matter how long it took to complete it.
11 Team America: World Police (2004)
Here we have a movie with all of the characters as puppets, and no I don't mean the Muppets. It's not that this scene is necessarily gross. It's just really awkward because it's one of the longest sex scenes I've ever watched, but it's all with puppets. Also, they go through just about every position imaginable. I was surprised by it at first, but then I saw the names of the South Park creators on the credits and that explained it. The movie is definitely action packed with explosions and fights and a Kim Jong Un parody.
10 Zombeavers (2014)
Here we have another one that is on Netflix. Here we have yet another dumb teenagers in the woods story. (When will these kids ever learn?) These five teenagers go up to a cabin for a trip. The beavers have been living in a river that had nuclear waste poured in it. So, the beavers turn into flesh eating zombie animals. There are a lot of gory scenes of people getting bitten. But, the one that takes the cake is the scene where a couple is having sex that ends with the boys male member being bitten off - because the couple having sex in the horror movie always gets targeted.
9 Requiem for a Dream (2000)
This is a good, unique movie...that you'll only want to watch once. It was filmed in "hip-hop" style. Meaning there were short choppy scenes. It follows a group of people sinking into drug addiction. There are plenty of "naughty" and disturbing things in this movie. There is the mother that goes on a diet trying to lose weight with the help of uppers. The directors had Jared Leto and Marlon Wayans go without sex and sugar for a month before filming, so they could understand what a craving is. The refrigerator in the hallucination scene was melted from the inside by the light elements.
8 Basket Case 2 (1990)
This strange 1990 movie follows a character named Duane and his mutant brother, Belial, who is bucket-bound. It picks up right where the original Basket Case left off. They are taken to a local hospital after falling from a hotel room. Their attempt at living a more private life is completely ruined after that. Duane's long lost aunt comes to help Duane and Belial escape the hospital and to escape the media. They go to the aunt's house which is home to many other mutants hiding from society. The gross scene in this movie involves some of the mutants having sex, and yes it is as bad as it sounds.
7 The Evil Dead (1981, 2013)
This horror classic follows a group of teenagers staying in the woods because that's always a good idea in a horror movie. The five teenagers encounter some flesh possessing demons. They find a mysterious book and read incantations out of it. After the demons are released, the teenagers all struggle to survive the night with only one lasting until morning. The gross scene here is the famous "tree rape" scene toward the beginning. Yes, you read that right, a tree branch raped a girl. The scene was recreated in the 2013 remake as well. Both are pretty gross in their own right.
6 Cabin Fever (2002)
I remember seeing this one. Here we have another story of teenagers in a secluded cabin in the woods. Except this time, they are faced with a flesh eating virus. The virus is passed through the water when the unknown patient zero is found dead in the fiver. The teenagers one by one keep getting infected. It kills them by eating their flesh. There is one guy that hides in the cabin and keeps himself from getting infected only to be shot by cops when the cabin is raided. They made two sequels to it. The gross scene I'm referring to is between one of the male leads and one of the girls. They are seen lying in bed together, and he starts touching her, surprised by how wet it is. They pull back the covers, only to be shocked the entire crotch area was bleeding and the skin was sloughing off.
5 Pink Flamingos (1972)
Here is the odd John Waters film, Pink Flamingos. It follows a Baltimore criminal named Divine, who is fighting to earn the title of "the Filthiest Person Alive" on a tabloid magazine. She (he?) is seen acting dog poop off the ground, which was real dog poop. Her reaction to eating it is real. The "chick with a d**k" was a real pre-op transgender person who had been taking hormones to develop breasts and other female features. She had her Sexual Reassignment Surgery a week after filming, and was the female star in John Waters' next film, Female Trouble.
4 Secretary (2002)
Just in case the image above doesn't get the point across, let me tell you about this movie. Maggie Gyllenhaal plays a girl that has just been released from a mental hospital. She takes a job as a secretary to a demanding lawyer. But soon his demands lead into a sexual sadomasochistic relationship. There are also scenes of Maggie's character crawling on the floor and getting spanked.
Trivia: The lawyer is named Mr. Grey which is the same name used in the famous 50 Shades of Grey: just a coincidence. This is one of the few mainstream movies that does not show BDSM as abuse, but rather as an activity between consenting adults.
3 The Girl with the Dragon Tattoo (2011)
Here we have The Girl with the Dragon Tattoo. It is an American version of the Dutch movie. It is based off of a book series by Stieg Larsson. It stars Rooney Mara and Daniel Craig. The story follows a disgraced journalist investigating a disappearance case from 40 years ago. He is aided by the punky hacker, Lisbeth Salander, played by Mara. They uncover a lot of corruption. Mara's piercings were all real including the nipple and eyebrow rings. But, the naughty scene in the movie is a full-on rape. David Fincher went all out to make the rape scene just like the one in the book.
2 Deliverance (1972)
Here we have the well known classic from the 70's. It follows a group of men going on a river rafting trip in northern Georgia. The rape scene with Warren Beatty was filmed in one take because he didn't want to repeat it. The original script had the lines in the scene consisting of swear words; the "squeal like a pig" line was added to "clean up" the movie. To minimize cost, the production was not insured. All of the actors did their own stunts. Donald Sutherland turned down the film because of the violence, but he later said that he regretted that decision.
1 9 1/2 Weeks (1986)
Here we have a very erotic 80's classic movie. This is about a couple (Kim Basinger and Mickey Rourke) that embark on a kinky affair. She is a recent divorcee looking for a little bit of an adventure after her divorce. It has the famous scene of her blindfolded while Rourke rubs a melting ice cube all over her body. As you can see in the picture above, she also dons a mustache and tuxedo and pleases him with that. She did use a body double for the nude scenes in the movie. It is basically softcore adult entertainment in a mainstream movie.