A commonly used phrase originating on call of duty video game referring to claymores. Claymores are similar to rat traps because it is a trip mine that will go off as soon as a player walks into it or by it. basically meant to demean the player that walked into the trap by implying he was as stupid as a rat for walking into his/her own death. also referred to as mouse traps if you are trying to demean the player using them as if to imply they are scared of mice.
LOL man I just hit that dude with a rat trap!
What a camping punk cant win without using mouse traps.