The Hangover is a 2009 American comedy film directed by Todd Phillips, and written by Jon Lucas and Scott Moore.

The film stars Bradley Cooper, Ed Helms, Zach Galifianakis, Heather Graham, Justin Bartha, and Jeffrey Tambor.

Lucas and Moore wrote the script after executive producer Chris Bender's friend disappeared and had a large bill after being sent to a strip club.

It became the highest-grossing R-rated comedy ever in the United States, surpassing a record previously held by Beverly Hills Cop for almost 25 years.

Two days before his wedding, bachelor Doug Billings travels to Las Vegas with his best friends Phil Wenneck, a sarcastic secondary school teacher, Stu Price, an apprehensive dentist, and Alan Garner, his odd future brother-in-law.

Retracing their steps, the trio travel to a hospital, discovering they were drugged with Rohypnol, causing their memory loss, and that they went there from a chapel the previous night.

While driving the car, they discover a naked Chinese man named Leslie Chow in the trunk, who attacks the trio and flees.

He shows them security camera footage of their immature behaviour from the night before and stealing the tiger with Doug, indicating they did not lose him until after they got back to the hotel.

Unable to find Chow's chips, Alan, with help from Stu and Jade, uses his knowledge of card counting to win $82,400 playing blackjack.

Alan finds Stu's digital camera containing photos of the debauchery from the night in Las Vegas, and the four agree to look at the pictures before deleting them.

Vinson had gone missing from his own Las Vegas bachelor party, blacking out and waking up "in a strip club being threatened with a very, very large bill I was supposed to pay".

[12] It was then rewritten by Jeremy Garelick and director Todd Phillips, who added additional elements such as Mike Tyson and his tiger, the baby, and the police cruiser.

Helms also said the fact that the story of the three characters growing closer and bonding forged the friendship between the three actors: "As you spend 14 hours a day together for three months, you see a lot of sides of somebody.

"[10] Lindsay Lohan was in talks with Phillips for the role of Jade in the film but was ultimately not cast due to being considered too young for what was discussed.

While the hospital, the police station, Mike Tyson's house and several interior scenes were filmed on soundstages in the Los Angeles area, other Vegas locations included the exteriors of Atomic Liquors and the El Cortez Hotel and Casino on Fremont Street.

The scene where Mr. Chow jumps out of the trunk of the Mercedes-Benz 220SE and assaults the protagonists with a crowbar was filmed at the intersection of East Mandalay Bay Road and Haven Street, which remains a dirt lot adjacent to the Las Vegas Strip.

He said the most difficult day of shooting was the scene when Mr. Chow rams his car and attacks the main characters, which Helms said required many takes and was very painful, such as when a few of the punches and kicks accidentally landed and when his knees and shins were hurt while being pulled out of a window.

[10] The missing tooth was not created with prosthetics or visual effects, but is naturally occurring: Helms never had an adult incisor grow, and got a dental implant as a teenager, which was removed for filming.

[21][22] The film uses the Kanye West song "Can't Tell Me Nothing" for which Zach Galifianakis made an alternative music video.

[3][24] Out of all R-rated films, it is the sixth-highest-grossing ever in the United States, behind The Passion of the Christ, Deadpool, American Sniper, It and The Matrix Reloaded.

[28] Although initial studio projections had the Disney·Pixar film Up holding on to the number one slot for a second consecutive weekend, final revised figures, bolstered by a surprisingly strong Sunday showing, ultimately had The Hangover finishing first for the weekend, with $44,979,319 from 3,269 theaters, averaging $13,759 per venue, narrowly edging out Up for the top spot, and more than twice that of Land of the Lost, which finished third with $18.8 million.

The site's critical consensus reads, "With a clever script and hilarious interplay among the cast, The Hangover nails just the right tone of raunchy humor, and the non-stop laughs overshadow any flaw.

[36] A. O. Scott of The New York Times praised Cooper, Helms and Galifianakis for their performances in the film as well as Todd Phillips for its direction.

[40] Conversely, Richard Corliss of Time said that "virtually every joke [in the film] either is visible long before it arrives or extends way past its expiration date" and added, "Whatever the other critics say, this is a bromance so primitive it's practically Bro-Magnon.

"[42] Joe Neumaier of the Daily News gave the film two-and-a-half out of five stars and noted, "Amusing as it is, it never feels real.

"[72] As a result of the film, Hangover-themed slot machines became popular at casinos throughout the Las Vegas Valley, the Caesars Palace gift shop sold tens of thousands of Hangover-related souvenirs, and the Las Vegas Convention and Visitors Authority received numerous inquiries from persons interested in recreating some of the film's most wild scenes, such as those involving a tiger.

[74] In 2018, Hasbro issued a parody version of their board game Clue where players have to locate a missing friend somewhere in the city after a wild night of carousing.

Principal photography of The Hangover Part II began in October 2010, with Bradley Cooper, Ed Helms, Justin Bartha, and Zach Galifianakis returning, in addition to Ken Jeong who appears in a much larger role.