Forgive me, but is there a parrot in the house?
One of the signs mentioned above is also used, so I am lead to believe by my son, to be a sign used by the infamous Grey Wolves. These are ultra-nationalists Turks, well known to many an unfortunate Christian.
i to learnt two different but related signing systems for those with disabilities and the first grew organically within the deaf community, and is not as far as I am aware something grafted onto them as cover for something else. Indeed the history of their signing is that the great and the good, and not so good, ignored, scorned or suppressed their signing.
However, hand signals have been used, as have other symbols and words, throughout history as a method of distinguishing 'us' from 'them'. As far as I know the sign language of deaf people is just that, a language between folk who share it in common, and not a cover for something else.
Now my only concern is someone feeds that blooming parrot...........