@force and the FORCE muf primitive can be used on objects of type THING, if they have the ZOMBIE flag set. Objects act as if they have the permissions of their owner. If an object is locked against a player, it will also be locked against anything that that player owns, that tries to test the lock.
Things with the ZOMBIE flag set cannot enter rooms or use exits that have the ZOMBIE flag set. This allows a way to prevent zombies from entering areas where they are not wanted.
If you try to run a program that you control, that has its ZOMBIE flag set, it will drop you into the MUF debugger. This lets you step line by line, or instruction by instruction through a muf program, setting breakpoints to stop at, and other nice things. There is help available within the debugger, via the 'help' command.