A tapper allows you to disconnect your network connection via a hot key so you can run around and shoot players then reconnect. This tool doesn't work in most games, excluding combat arms. You usually have a max of 10-15 seconds to perform your deeds before being disconnected from the game client side.
If you are wire savvy, try building an ethernet tap switch, it works pretty much every game. I have a switch on the front of my case which allows me to do this.
Hope this answers any current and future questions.