Sounds of disapproval are a form of nonverbal communication used to express dissatisfaction or disapproval. TUTS, HISSES, BOOS, TSKS, TSKTSK, and CATCALLS are all examples of sounds of disapproval. TUTS is a short sound made with the tongue against the roof of the mouth. HISSES are a sharp, high-pitched sound made by forcing air through a small opening. BOOS are a loud, deep sound made to express disapproval. TSKS are a short, sharp sound made with the tongue against the roof of the mouth. TSKTSK is a sound made with the tongue against the roof of the mouth twice in quick succession. CATCALLS are loud whistles or jeers made to express disapproval.