a way of dislocating the tongue to mispronounce or misrepresent words. The Qur'an accuses the Jews of doing this to distort the clear meaning of the Scriptures. see also Jews, dislocate...
* Abd-Alqadir, an Urdu translator of the Qur'an explains how this is done:
They used the word Raina as has been mentioned in Sura Bakr (al-Baqarah 2:104). Thus when the prophet addressed them they used to reply, "We have heard" -- which meant, "We have accepted." But they would add, inaudibly, "We do not believe," that is, "We have only heard with the ear and not the heart." When they addressed the prophet they said, "May thou not hear." The ostensible significance of this expression is an invocation of good -- be thou victorious so that thou may not hear an evil word from anyone. But in their heart they intended to say, "So thou become deaf." Such wickedness they used to perpetuate. (Cited by Muir, The Beacon of Truth, p.169,170)
* Jalaluddin also explains that "twisting of tongues" is the same as "dislocating". (Cited by Muir, ibid, p.170)