(If you need to ask what a "Logic Bomb" is, go look here. They explain it better than I could.)
Like the kind of creep who uses Sudafed and fertilizer to make explosives in the garage--I give you our home made logic bomb:
My vacuum cleaner sucks. It doesn't suck.
My vacuum cleaner doesn't suck. It sucks.
Feel free to use it the next time you are held captive by an evil supercomputer!