Well, to start, if you aren't causing yourself any pain or discomfort, it may just be a nervous tic, like some people that bite their nails or tap their foot. If you are causing yourself pain, or if you feel like you can't control it even if you try, their might be some more insidious underlying psychological or neurological problems (see Tourette's syndrome or Trichotillomania, perhaps?)
It has no meaning. She was probably just nervous.
It means they snort stuff like cocaine and are rubbing it in desire.
it means he likes you = )
This is a type of masturbation. A boy (men usually don't do this) rubs his genitals against something or someone. Often, this is without the other person's permission. A more formal term for this is frottage.
When he rubs his but on the floor,Could mean hes just itchy , Or has Worms ,And if hes not eating ., It's probably worms.
Nothing.
it means she is horny
he is showing you affection
He feels bad and cares for you
It might mean that she feels intimate about you... or her feet are cold.
He has an itch, and may sneeze.
That means he wants to have sex with you