At the very least the may not like you...or maybe they just don't like what your saying at the moment. According to behavior analysis they are subconsciously saying f-you or f-your comment...however they may genuinely be unaware of their actions.
But in my culture the middle finger means fukk you! But these people place their middle finger accross their mouths like it's resting their "middle finger" there. Are these people really just resting their finger with no ill intent at all?Like out of all their of their fingers it had to be the middle finger? I mean like I've done it just to try it and it's an odd position to place a finger, it's kind of uncomforatble even. Have you ever done this does it really mean to fukk off?