A piece of hardware you splice into your network connection to use as an aid for cheating. It is designed to temporarily block information from getting from the game server to your system. Other users may see you as occasionally having a very high ping, over 1,000, because you're preventing game updates from coming to you, but you will have a low ping for sending YOUR updates to the game server. For even more details on how this works, read Wikipedia's article on this.
It is unconfirmed whether these even work with Warhawk.