Am I positively charged or negatively charged? We often hear that the human body has a weak electrical charge.  Is it a positive charge or negative charge?  Or maybe different parts of me have different electrical charges?  Or maybe there's a complete electrical circuit inside of me?
Now suppose I scuff my feet on the carpet and touch metal objects to make sparks.  Does any of that affect my electrical charge?  Which direction do the sparks travel?
Or maybe a buildup of static electricity is a completely different phenomenon from inherent electrical charge.  Even so, why doesn't the buildup of static electricity interfere with my internal electrical flow?  It certainly does with old TVs and electronic equipment!
What if two people are scuffing their feet on the carpet and touching each other?  You would think that both people, being electrically identical, would have the same charge.  Why then would there be a spark at all?  And which direction would the sparks travel?
 A: 
We often hear that the human body has a weak electrical charge. Is it a positive charge or negative charge? Or maybe different parts of me have different electrical charges? 

The Earth has a slight negative charge, so by default you have a slight negative charge, if you are standing directly on bare ground without shoes. Since you're a conductor, you can't have positive charge in some areas and negative in others, it should even out.

Now suppose I scuff my feet on the carpet and touch metal objects to make sparks. Does any of that affect my electrical charge? Which direction do the sparks travel?

Yes, you build up charges as you rub your feet on the carpet. The direction of charge flow depends on the relative positions of the materials in the triboelectric series. For example, human skin is very high on the series, so if you do this barefoot, you're almost guaranteed to get a positive charge no matter what the carpet's made of. But nylon is higher on the series than cotton, so if you wear cotton socks on a nylon carpet, you'll get a negative charge.

Why doesn't the buildup of static electricity interfere with my internal electrical flow?

Since you are a conductor, in equilibrium the excess charges will gather on your skin and create no electric field inside your body. Of course, an actual electric field in your body would have significant effects.

What if two people are scuffing their feet on the carpet and touching each other? You would think that both people, being electrically identical, would have the same charge.

If they really were identical, there wouldn't be a spark. It's just that it's quite likely they'll have different shoes, walk on the carpet different amounts, and so on.
A: In my experience, people who get a shock from touching doorknobs are positively charged. The charge is positive because the deflection of an electroscope touched by them diminishes when a negatively charged pvc rod is approaching. Typically the person got the positive charge from sitting in a chair with a synthetic seat. The leaves of an electroscope rise when the person is standing up from the chair, because the work of  removing the positive body from the negative seat creates a high voltage, as in an electrophorus. 
In my experience, walking around on rubber soles, and even rubbing your shoes in the carpet, in itself does not cause a deflection of the electroscope. Of course, if a person was already charged by rising from a chair before walking around on insulation shoes, that charge will cause a deflection of the electroscope, and finally a spark to the doorknob.
