When he wasn't busy tossing beer cans to Matthew McConaughey in New Orleans over the weekend, Brad Pitt hosted his annual Make It Right gala. Bruno Mars was one of the performers during the charitable night, but Brad couldn't stay off the stage! He grabbed a tambourine and joined Bruno during a performance of "Sex Machine," dancing in the background while Bruno shouted "Benjamin Button!" to the crowd and exclaimed, "Brad Pitt, you sexy mother f*cker!" Watch the video for yourself above.