Any super-lame way of doing things that has not yet been codified into being a science. Every form of knowledge one is too lazy to investigate is magic.
Magic is not to be confused with chaos or improbability. Magic is bound by rules, even if these are often poorly understood and can be shored up by a 'theory' of how actions work and why they do what they do, whereas chaos, and improbability apparently cannot.1) 2) Plus, magic is blue, chaos is the reddish-black of dimming coals, and Improbability is green. Duh.
Some people have been known to use magic: Cheshire Cat, Rosin, Akitsu, Harry Dresden, Kuroiten, Paul Lo, Merlin . . . 3)