Jessica Alba photobombed by Jackass' Johnny Knoxville

While posing for photos in her citron skirt and simple white top at the MTV Movie Awards on Sunday, beautiful Sin City star Jessica Alba, 32, was photobombed by the Jackass' daredevil Johnny Knoxville, 43, who jumped behind her in the photograph.

She took the prank pretty well, laughing when she turned around and saw Knoxville with a mischievous smile on his face.