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.
"Humping" typically refers to an action where someone thrusts or rubs against something or someone in a sexual manner. It can sometimes be seen as inappropriate or aggressive behavior.
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
It might mean that she feels intimate about you... or her feet are cold.
He has an itch, and may sneeze.
From my personal experience it means they are over tired.