nah

a typically turkish cultural gesture which expresses misbelieve, distrust, challenge, opposition or disobedience.
nah occurs when someone puts his/her thumb between forefinger and middle finger and the nahhed fist is shown to the person at whom it is aimed.
a more brutal version of the gesture exists, by creating a "slash" like sound after turning the nahhed fist with an immediate forward motion, in order that the nahhed wrist hits the other hand’s palm.
(bkz: ingilizce entry girmek)