So they accurately portrayed a crazy person by getting Matthew McConaughey to be himself. The next time you go back and watch True Detective, imagine him doing that chest thumping song before every shot. You're welcome!

Paramount Pictures
This explains why the True Detective makeup people put his facial hair on crooked.

Oh, and we should mention that this movie also featured a "not-so-fake punch" incident. In one scene, Hill's character freaks out and lectures his drug dealer, who responds by cold-cocking him. Scorsese wasn't happy with early takes of the scene, so he went to Jonah Hill and asked, "Hey, kid, you wanna try one where he hits you for real?"

Now, keep in mind that the dealer was played by Jon Bernthal, who boxes in his spare time and looks like he works out in a prison yard. Hill, meanwhile, is the quintessential "before" picture from a late night weight loss infomercial. But Hill didn't want to look like a wimp in front of his idol, so he gave in to peer pressure and quite literally took one for the team. The punch was so hard, it sent the fake teeth Hill was wearing flying. It almost looks like he gets knocked out cold, but he's just lucid enough to hear Scorsese's concern as he yelled, "His face is swelling! Get him new teeth and let's shoot it!" Oh, no, he wasn't concerned for Hill's health -- he was worried about missing a good shot.

For example, basically every fight in Rocky IV contains real punching, and that's saying something, considering that the movie is a Cold War drama told almost entirely through fisticuffs. In one particularly brutal scene, Dolph Lundgren claims that Sylvester Stallone tricked him by saying he'd punch on the count of three, but then swung on two.

"Sorry, I was counting in American."

Lundgren got his revenge, and then some, during a fight where Stallone said, "Fuck this acting shit, let's have you try to knock me out for real" (or something to that effect). Lundgren did as he was asked, probably with glee, and hit Stallone in the chest so hard that he had to spend nine days in a hospital to get his heart working properly again. The insurance company refused to believe it until they broke the scene down frame by frame and were able to pinpoint the exact moment where Stallone's heart breaks.

MGM
Ah, there it is.

But like we said, this happens more often than you'd think. One of the most famous scenes in Fight Club, another film known for its brutality, features some good old-fashioned improvised violence. When Brad Pitt insists on having Edward Norton hit him, the script called for Norton to clumsily smack Pitt's shoulder to emphasize his lack of fighting skill. But director David Fincher told Norton to actually give Pitt a good, hard punch to the ear.

After some protest, in which Norton pointed out that he had basically just met Pitt and was being told to punch him in the head, he agreed. Pitt's surprised reaction is genuine, and you can even catch Norton laughing afterward.

20th Century Fox
And if you look really closely, Edward Norton actually punches himself in the ear.

Meanwhile, in Goldfinger, Harold Sakata, the actor who played Oddjob, didn't quite understand the concept of pulling his punches, so the look on Sean Connery's face and his video-game-glitch body contortions after Oddjob wallops him on the back of the neck are genuine.

United Artists
"Ugh, dammit! I didn't even get to do the fourth sex scene yet!"

You've got to respect Sakata, though, because he was as committed to taking pain as he was to giving it. Something went wrong with the special effects during the scene where Bond electrocutes Oddjob, and Sakata badly burned his hands on the metal bars. When the director asked why he never let go despite being in obvious pain, he casually replied, "You didn't say cut, so I just hung on," a line more badass than any of the dialogue delivered by Bond himself.

United Artists
They made sure his hat conducted electricity for that extra dose of authenticity.

Their suspicions are heightened when Damien and his mother visit a safari park and all the animals collectively lose their shit. Some flee in terror, while others attack, as the animals seem to be able to instantly identify the Antichrist by the same rule that lets dogs sniff out Terminators.

20th Century Fox
"Hey, kid, how are ... oh, hey, you're super evil. See ya!"

In one especially memorable scene, the baboons decide they're going to do humanity a solid and attempt to murder Damien. Audiences were impressed by the acting of Damien's mother, played by Lee Remick, as she manages to convince you that she really does have a crippling fear of baboon groins.

20th Century Fox
"IT'S LIKE A CHERRY POPSICLE."

But that fear is real -- the baboons really did freak out and attack the car. At first Remick stalled the vehicle because she wasn't used to driving with a manual transmission, and then she was too busy panicking to try to get it going again. Damn, who would have thought that slowly driving a strange contraption through the territory of a bunch of violent and aggressive animals would backfire?

So when you're watching that scene, you're watching a woman who's fully convinced that she and the child actor in her care are about to be beaten to death by angry apes. Eventually the crew managed to shoo enough of them away for Remick to settle down and get the hell out of baboon country. And, as usual, the best take was the one where the actor was in real mortal terror.

Like almost every Martin Scorsese movie, Goodfellas features a vicious sociopath fueled by drugs and rage who does horrible things to rise to the top of his field, only to realize too late that what he's achieved has cost him everything. In Goodfellas, this role is played by Joe Pesci, because of course it is.

Warner Bros. Pictures
You'd think the mileage problems caused by trunk bodies alone would make him see reason.

After Pesci and his two gangster pals beat a rival criminal to death, as gangsters tend to do, they stuff the body in the truck and head to Pesci's mom's house to borrow her shovel (why a psychopathic career criminal doesn't have his own body-disposing shovel is unexplained, but never mind that now).

Warner Bros. Pictures
Maybe he keeps it at his mother's place. Rent is expensive.

They try to sneak in without waking her up, but she catches them, and they're forced to improvise a story about hitting a deer to explain the blood on their clothes. At this point, hilarity ensues, as a somewhat confused old lady says confused-old-lady things, shows them a painting she made, and makes them eat a spaghetti dinner in the middle of the night -- oblivious to the fact that her son is a violent murderer. It almost feels like the trio of ruthless killers has wandered into a family-friendly sitcom.

The scene rambles on like that because it's almost completely unscripted. The woman playing Pesci's mom is actually Martin Scorsese's mother, Catherine, and she didn't know the context of the scene -- her (real) son simply told her that Joe Pesci had turned up for the first time in a few days at an odd hour, and that she should feed him and his friends and show them her lousy painting. All the dialogue was improvised by the three actors and Catherine, who had no idea that her cinematic offspring had just parked murder evidence in her driveway.

While Catherine must have thought that Martin was directing a very boring movie, she gamely plays the loving mother who dotes on her offspring and sees no problem with Pesci borrowing a huge kitchen knife. After all, he needs to chop up that poor deer. Maybe Marty's making some sort of animal rights movie?