The Chin Flick
Among all of the possible hand gestures that can be misinterpreted around the world, the chin flick may be the least confusing. So if you have a habit of flicking your chin while you talk, don't sweat it too much. In much of Italy, people will make the gesture — which involves placing the fingertips of one hand under your chin, pointing at your neck, then flicking them out towards the person with whom you're speaking — to indicate they couldn't care less (about you, what you're saying, your dog, the scrape on your pinkie). Frankly, my dear, they just don't give a damn. It can also mean they're positively not willing to do something [source: Marchetti].
In Northern Italy, France, Belgium and Tunisia, the chin flick can be used to tell someone to get lost (in a little bit more aggressive language than this) [source: Heddleston]. And speaking of aggressive, if someone wants to be quite emphatic about their intended message, they will make the gesture quite forcefully.