What causes someone to black out drunk?

Alcohol is a poison that never did anybody any good, ever, so stay away from it. It will destroy your brain cells, damage testicular cells that make testosterone, facilitate development of cancer in many organs, cause hepatitis, cirrhosis and pancreatitis etc. There is no safe level of alcohol intake. Quit while you are ahead.

Dr Singh provides good advice, and this should be heeded. Alcohol acts as a sedative/ tranquilizer and too much causes drowsiness, dizziness, confusion and eventual "black-out", even coma with larger overdosing. Imagine you were driving if this occurred, and the associated risks. "A word to the wise..."