Getty Images for Clara Lionel Foundation

We knew Brad Pitt had a wicked sense of humor, but who knew he was capable of making Rihanna blush?!

Last night the 50-year-old actor made a bit of a surprise appearance at the First Annual Diamond Ball at The Vineyard in Beverly Hills, which benefitted Rihanna's Clara Lionel Foundation. Jimmy Kimmel hosted the event and introduced Brad, who then gave a speech and introduced Rihanna. But it wasn't just any speech -- it was more of a roast!

Angelina Jolie's hunky hubby started off in a very serious tone, and as an image of a very young Rihanna appeared on the screen behind him, he said, "I've often asked the very questions you yourself are asking right now—what the f*ck went wrong?"

"I give you exhibit A," he said. "Look at the young girl before you, all full of hopes and dreams, living a humble existence in Barbados, her whole life ahead of her." Pitt added that RiRi "soon fell in with a bad crowd led by the dubious and nefarious character known as The Jay Z."

"For those you not in the know, The Jay Z was an evil impresario known for turning out hit records and ripping insane lyrics and fresh beats," Brad continued. "Needless to say it was all downhill from there." Brad then praised Rihanna for selling 54 millions albums, winning seven Grammys and having "only 90 million Facebook fans and 40 million Twitter followers," but when a Photoshopped image of an overweight Rihanna on a couch popped up behind him, Brad joked, "I ask that we stand together by her side and show her our support and our love and say to her the hard words, 'Rihanna put down that sandwich, get off your *ss and do something. God damn it, just do something with your life.'"

So how did Bad Gal RiRi get Brad to show up? "Brad Pitt loves charity, he loves giving back and it was just as simple as that," she told E! News' Marc Malkin on the red carpet. "He was honored to be a part of it, so I'm really happy he's here." That was easy!

Getty Images for Clara Lionel Foundation