Different people have different definitions for speedballing. Some say speedballing is when you do intense uppers and intense downers at the same time. Say... snorting or shooting cocaine immediately followed with something such as xanax. However some say, it's when you shoot a pain killer such as heroin or morphine followed by shooting an upper such as cocaine. When doing this, some people will shoot a syringe of water between the two drugs. This is supposed to get the drugs flowing through your body faster.