When an actor takes on a role, they set out to build a believable character from the ground up. Besides memorizing lines, they often have to research the era the movie takes place, learn about their character’s profession, or maybe even work with a dialect coach to help them create an authentic portrayal onscreen.

But that’s not the only way actors dive into their characters. You might not believe it, but there are countless instances where celebrities were either drunk or stoned while filming some of your favorite scenes (or entire movies). Whether the role required it, or the production was so terrible they did what they could to get by, you’ll be stunned when you find out which actors were really drunk or stoned on set!

1. Ethan Embry (Can’t Hardly Wait): Since filming this classic ’90s teen party film, Embry has admitted on record that he was a pretty big pothead at the time. He was so stoned while filming that he claims he can’t even remember the plot of the film—besides the fact that it’s about a party.

2. Olivia Wilde and most of the cast (Drinking Buddies): Most productions that feature scenes where the cast is consuming alcohol use non-alcoholic drinks. But that wasn’t so on the set of Drinking Buddies! In fact, every time you see someone take a sip of beer, they’re legitimately drinking.

3. Daniel Radcliffe (Harry Potter): While he admits to partying pretty hard—and showing up to set still drunk from the previous night—Radcliffe maintains that he never actually consumed alcohol while filming.

4. Brad Pitt and Edward Norton (Fight Club): In a classic scene from this ’90s film, Pitt and Norton are drunkenly hitting golf balls at night. It turns out that, in order to prepare for the scene, both actors actually got pretty wasted. Talk about method acting!

5. Jennifer Lawrence (Hunger Games: Catching Fire): The leading lady in this incredibly popular book series-turned-movie franchise told David Letterman during an interview that she had a little too much fun one day while shooting and drank a few too many piña coladas on set with some of her cast mates.

6. Martin Sheen (Apocalypse Now): Many actors who starred in this classic Francis Ford Coppola film have openly talked about how poorly run the set was. In this particular scene, Sheen was said to be so drunk that he actually punched a mirror—and bled on most of the set pieces.

7. The Beatles (Help!): It’s no secret that the Beatles were rather experimental when it came to drugs and booze. In fact, Paul McCartney and Ringo Starr have both admitted they were pretty stoned when they filmed the scene with Dr. Foot and Algerman in the Alps.

8. Natalie Portman and Mila Kunis (Black Swan): One of the more memorable scenes in Darren Aronofsky’s psychological thriller required Portman and Kunis get very intimate. As expected, they were nervous when it came time to film, and an inside source at The Hollywood Reporter claimed they downed an entire bottle of tequila together before cameras started to roll.

9. Pretty much everyone (Dazed and Confused): It’s only fitting that the cast of a film about teens getting drunk and high on their first night of summer break would really get into their roles. Even though the marijuana used on set was not real, the actors admitted they had their own that they’d smoke between scenes.

10. Shia LaBeouf (Lawless): Since LaBeouf played a Prohibition-era moonshine bootlegger in this film, he decided to really get in character. He drank so much that it gave his character a heavier look, which he thought helped to enhance the authenticity. This drinking, however, didn’t go over well with the rest of the cast, as some actors threatened to quit after being annoyed by him.

11. Fred Astaire (Holiday Inn): For the hilariously clumsy drunken dance scene in this classic, Astaire was said to have consumed two bourbon shots prior to filming. Then, he downed one additional shot before each take! It took them seven takes to get it right, and by then, he was completely wasted.

12. Julie Andrews (The Sound of Music): The farmer who owned the land where the crew filmed the famous “Do-Re-Mi” scene actually brewed his own Schnapps, and he would give Andrews shots while she practiced her guitar in between takes!

13. John Leguizamo and Bob Hoskins (Super Mario Brothers): These two actors were apparently so miserable during the filming of this adaptation of the popular Nintendo game that they were drunk almost the entire time. Leguizamo would reportedly bring scotch to the set, where he and Hoskins would heavily indulge while drowning their creative sorrows.

14. Billy Bob Thornton (Bad Santa): Thornton portraying a grungy mall Santa Claus whose drinking was just the beginning of his problems made for an instant comedy hit. Rumor had it that Thornton actually imbibed about as much as his onscreen character when he wasn’t filming.

15. Margot Robbie (The Wolf of Wall Street): Robbie’s breakout role in this Martin Scorsese film  had her working alongside A-list celebrities like Leonardo DiCaprio and Mathew McConaughey. She reportedly was so nervous before her first intimate scene with DiCaprio that she threw back three shot of tequila to calm her nerves!

16. Johnny Depp (The Rum Diaries): Depp has been pretty open about his struggles with alcohol in his personal life. His character in The Rum Diaries frequently overindulged in booze, so the director made sure to keep a bottle of Chivas Regal on set at all times so Depp could truly get into character.

17. Robert Pattinson (The Rover): Pattinson shed his clean-cut look for this movie where he played a criminal on the run. He was reportedly drinking large quantities of vodka while filming to give his character a rough-around-the-edges demeanor.

18. Denise Richards, Matt Dillon, and Neve Campbell (Wild Things): This movie was infamous for its steamy ménage à trois. Naturally, they were all a little nervous about the whole thing, and according to Campbell in an interview with Entertainment Weekly, the three stars got “slightly drunk” on tequila before shooting began.

19. Robert Shaw (Jaws): There’s one scene in Jaws when the captain of the boat, played by Shaw, delivers a drunken speech to the crew. Shaw apparently got so drunk before he filmed the scene that he blacked out, and the film crew needed to reschedule the shoot for the following day!

20. Jason Mewes (Clerks): In an interview with Metro, Mewes (left) said during this cult hit that he was either drinking or smoking weed the entire time. He has since found sobriety, but it was so bad at the time that his director and costar, Kevin Smith (right), would frequently send him home.

Who would’ve guessed that these actors were actually drunk or high on screen? Okay, fine—for some of them, it might have been more surprising if they weren’t!

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