Rihanna let Michael Cera 'slap her a** for real' in This is The End if he agreed to one condition

Of all the wild things in This is The End, one of the craziest is an agreement made completely off-camera, which led to one of the most memorable scenes in the film.

For those who live under a rock, the film by Seth Rogen and Evan Goldberg, the names behind Superbad, focuses on a bunch of celebrities dealing with the end of the world.

The main cast is made up of Seth Rogen, Jay Baruchel, James Franco, Danny McBride, Craig Robinson, and Jonah Hill, all of whom play themselves.

There are more famous faces throughout the film, as an A-list party at the start of the movie features an absolute all-star attendance, ranging from Rihanna to Kevin Hart to Jason Segel.

While most of the cast play a heightened version of the public’s perception of them, the biggest change is how they wrote Michael Cera in the movie.

Cera portrays himself as a coked-up sexual deviant, something that Mindy Kaling finds incredibly hot, saying she wants to f**k him.

However, his most iconic scene involves him slapping Rihanna on the behind, for her to then rightfully turn around and smack the absolute sh*t out of him.

For those who haven’t seen, Rihanna very clearly does not hold back.

This is because, according to Seth Rogen, the two made a deal.

He told Sway’s Universe: “In the script, Michael Cera slaps Rihanna's ass and she doesn't hit him back.

“But he asked her, ‘Can I slap your ass for real?’ And she said, 'You can slap my ass for real if I can slap you back in the face for real.'"

Rogen reports they did the scene ‘three or four times’ and that she ‘smacked the f**k’ out of Cera.

Cera later spoke of the incident to GQ, saying:

“Yeah, I mean she definitely hit me, but I really, I wanted that, you know?

Rihanna smacks the sh*t out of him (Sony)

“I mean, I think it's a lot funnier and a lot more convincing… a fake slap just doesn’t look good.”

He went on to say of the slap: “She really sent me flying, and it was great.

“And now it's on film forever, this pain that I experienced.”

Rogen also said of the actual slap used in the film: “She cupped his ear and actually whacked out his equilibrium and he had to go lay down in his trailer for around half an hour.

“That's the take we used in the movie. We didn’t add any sound to that or anything.”