You know when you play as a sniper, and someone joins the game and decides to be a sniper too? And they decide that rather than flank around and take up position to cover your blindspots, they follow you like a lost puppy? And their aim SUCKS so badly that they unload their entire magazine in less than one second, produce enough muzzle flares to put up a big "I'M RIGHT HERE!" sign next to you, and still don't kill anything?
That guy.