In an MTV interview with the cast of 'This Is The End,' Seth Rogen admitted that Rihanna really did slap Michael Cera during one of the scenes. 

The singer took her comedic role pretty seriously, Rogen said, "Rihanna did slap the sh-- out of him."

The actor added, "For real, he said, 'I'm actually going to slap the sh-- out of your ass,' and she was like, 'I'm actually going to slap the sh-- out of your face then.' We did it like six times, and the last time, he was like, 'I don't think I can do this anymore.' " The singer apparently hurt his ear, pretty badly.