Denoting or relating to an attack made by one's own side that accidentally harms one's own forces.
The only thing more accurate than incoming enemy fire, is incoming friendly fire.
by caxwl July 08, 2004
Jargon used by police (blue) to indicate they are firing a weapon and that other officers should take care to avoid getting caught in the crossfire. In the 911 call transcript of the Tiger attack at the San Francisco zoo, an officer was heard announcing a "Blue on blue".
Officer is firing, blue on blue!
by Gorn Dog January 15, 2008