Picking Nose
I have to confess I pick my nose sometime, and am very satisfied by picking a lot of dried and hardened nasal mucus.
According to Wikipedia, "This is an extremely common habit, with some surveys indicating that it is almost universal, with people picking their nose an average of about four times a day." Former Chinese president was caught by the cameraman using his middle finger to pick nose in People's Representative Congress.
(http://en.wikipedia.org/wiki/Nose-picking)
I normally cut my little finger nail alternatively, and use that long nail little finger to pick the nose or my ear.
But in public, I will behave like a gentleman, use a tissue to blow my nose or just use my thumb and point finger to squeeze the nose a little bit.