the dictionary definition is "Fickle and irresponsible: "you may be seen as too flighty and lightweight for real responsibility"."

For that words use in slang i can it being used in a few ways. First, you can describe a person that flies a lot as a flighty person. Second, someone who travels or moves living locations can be described as flighty. Third, someone who is drunk or mentially unstable because of drugs may be called flighty.

I though have never heard or seen the word flighty being used before in Californian English.