(adsbygoogle = window.adsbygoogle || []).push({}); after host migration the peaple who lose there connection will just be standing there and you can shoot them but they cant die. it helps with doing perfectionist challenges. This was not found by me but this was found by "xINTIMIDATIONx" on "*****.com"

Or you can just wait till the enemy gets a helicopter in the air and then shoot a whole clip of your assualt rifle or sub machine gun into it and get the challenge that way. But that's a weird glitch you found.