A teammate in any cooperative venture that can often be found running ahead of the team, lagging far behind the team, veering away from the team to hunt for items, or simply failing to help protect the team due to a general lack of situational awareness. A Cornjerky often gets himself and his team killed due to his inability to stick with the team.
Teammate 1: Jesus titty-fucking Christ that Cornjerky guy just got us all killed! Where the hell did he think he was going?
Teammate 2: Cornjerky, pay the fuck attention! We just told you to stick with the team!
Cornjerky 3: Duh, shiny stuff over there!