blue-on-blue
adjective /ˌbluː ɒn ˈbluː/
/ˌbluː ɑːn ˈbluː/
[only before noun] (British English)- in a war, used to describe an accident or attack in which people are hit by a bomb or weapon that is fired by their own side
compare friendly fire(战争中)误伤己方的