How does carbon monoxide affect a smokers blood?

Well lets start with this, Carbon Monoxide hinders the ability to distribute oxygen throughout your body and in the body of someone who smokes  carbon monoxide passe will pass through the lining of the Lung into their blood, where it can attach to red blood cells.

It affects there lungs, heart and blood vessels

when you rub, you also apply pressure, that pressure can urge the poop to come out. i think that when your rubbing, you also might be slightly breaking it up and that can further fill the stomach.