1. To turn cables, lines, wires, etc. into an impenetrable knotted mess by incompetent handling or accident.
Originally nautical in origin, from the rat's nest appearance of poorly handled lines and tackle.
2. Any device, system or operation that has been hopelessly ruined, usual by sabotage or misuse.
1. Hey, what dipshit rat fucked this halyard?! I might as well throw the whole fucking mess to the fish.
2. Man, Billy-Bob sure rat fucked our plans to set up a meth lab in his trailer when the dipshit told Andy Taylor about it.