A plate you weld on top of your weld because you don't trust your welding.
Hey Joe what's with the bozo chicken plate on your suspension weld?
Internal hardend parts of Interceptor Body Armor, for instance. May also refer to hardend plates velcroed to flight body armor used by U.S. troops. They are supposed to be able to stop 7.62 rounds.
Make sure that you have your chicken plates in your vest before you go out on patrol. or It was hot as balls in that Chinook, I couldnt wait to land and at least take off my chicken plates and helmet.