Magic number (programming)

Time formatting and storage bugs, for problems that can be caused by magics

Sentinel value (aka flag value, trip value, rogue value, signal value, dummy data)

Canary value, special value to detect buffer overflows

Video games cheat codes which have the same origin

XYZZY (command)

image magic string

define magic string

wikipedia magic string

weblio magic string

kotobank magic string

jisho magic string