@nade,
Yes there is - I have a thread on it somewhere.
It is, when subliminally produced a signal that the producer is unsure/uncertain or mistrusting in/of themselves and/or of you or their current surroundings or actions.
Doesn't mean their intent is detrimental to you, nor does it imply genuiness (A word I tried to alter to 'genuinity' because it rolls off-the-tongue better, but failed.) .
An 'open' intended wink is a signal of incorporation into an event/gag/hidden agenda, etc.