Answer: The DASH diet -- DASH actually stands for Dietary Approaches to Stop Hypertension -- is a diet that's based on the USDA food pyramid and it was designed to reduce blood pressure, to control blood pressure.
Graffiti and graffito are from the Italian word graffiato (scratched). Graffiti is applied in art history to works of art produced by scratching a design into a surface. A related term is graffito, which involves scratching through one layer of pigment to reveal another beneath it.
But the earliest of the cultural references (listed by Wikipedia) is the 1975 film with that title, and it's reasonable therefore to assume that this is the origin of the phrase in popular culture. In that film, the title is clearly a pun on 'knight moves', since the central character is interested in chess.