Chopped and screwed, says Wikipedia, refers to a technique of remixing hip hop music which developed in the Houston hip hop scene in the 1990s. Thus Fine Arts class learned from Jordan Mitchell, student rap artist and record producer.
Mr. T had read about the phenomenon in the NY Times but had not heard any of the music. He immediately proclaimed the sludgy but shimmering sound, "the psychedelia of the new century."
Records are manipulated by slowing the tempo and applying techniques such as skipping beats, record scratching, stop-time, and effecting portions of the music to make a "chopped-up" version of the original.