If you’re not a gamer or Red vs Blue fan you may not get this, but a ‘team kill’ is when you shoot someone on your own side.  Team killing has a long and noble history dating back to humanity’s formative years.  The first team kill took place when Cain slew Able whilst planning the first Call of Duty. The most famous team kill took place on March 14, 44 BC when Brutus camped at Julius Caesar’s spawning point at a gladiatorial game and slew him. (Technically that statement is 100% accurate.)