Complex sentence: Blow's use of the term "magic underwear" is a disparaging reference to the Temple Garment worn by some Mormons,; "magic underwear" is a known term of derision used against member of the Mormon faith.
Split into simpler sentences: Blow's use of the term "magic underwear" is a disparaging reference to the Temple Garment worn by some Mormons. "Magic underwear" is a known term of derision used against members of the Mormon faith.