A random person or character in a real life setting or game.
When doing a 5v5 match in League of Legends with only 4 real life friends, you are certain to get a randomnig on your team.
Ballsack, don't make me lane with the randomnig please.
Who the hell is this randomnig behind me, damn.
Haha, check out those 3 girls and the randomnig