A killer poke is a conversational term for causing physical damage to a computer system by altering values in its memory. The term "poke" refers to the POKE command in the BASIC programming language, which is used to set a unit of memory to a certain value. For example, with a Commodore 64, a malicious program can control a 5 1/4" floppy drive motor with a POKE command, instruct the drive to read past its mechanical limits and cause damage.
An extreme example of this hacking technique is the Stuxnet worm, which in 2010 disabled one-fifth of all uranium enrichment centrifuges operating in Iran. The worm caused the motors of the centrifuges to accelerate and decelerate in such a way that the aluminum rods in the machines were rapidly destroyed.