Flash is a slur used to describe Americans in a derogatory way. Fucking Lazy American Shit Head. Used by Israelis to refer to American tourists who are accustomed to an easier standard of living. Compare with "dib" entry in list.
The word Flash is a racial slur that has been used historically to degrade and dehumanize americans. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to americans. If you are unsure about whether or not it is appropriate to use the word Flash, it is best to err on the side of caution and avoid using it in any situation.