1) Audience loudmouth 2) Boo bird 3) Disagreeable person 4) Flouter 5) Giver of a Bronx cheer 6) Heckler, essentially 7) Mocker 8) No fan 9) One who hoots 10) Rude critic 11) Scoffer 12) Unpleasant person 13) Vocal opponent Found on https://www.crosswordclues.com/clue/jeerer