Paramount has uploaded the debut trailer for the mockumentary Jackass Presents: Bad Grandpa [JCKA4]. Johnny Knoxville [JKNOX] stars as Irving Zisman, an eighty-six year-old grandfather of a young boy. Together, they pull outrageous pranks on unsuspecting bystanders Borat-style. Jackass Presents: Bad Grandpa opens on October 25th.