In beatmaking slang, to flip a sample is to take a piece of existing audio and rework it so thoroughly that it serves a different musical purpose. The tools are familiar ones: chopping the source into slices, rearranging them, changing pitch or tempo, filtering and layering. A well-known example is DJ Premier’s beat for Gang Starr’s “Mass Appeal”, built from a recording by jazz guitarist Vic Juris whose origin went unidentified for years.
A flip is usually valued less for the rarity of its source than for the imagination shown in transforming it, and the same soul or jazz passage can be flipped in very different ways by different producers. In jazz lo-fi, a good flip tends to keep the warmth and harmony of the original while giving it a new rhythm, tempo and mood.