Alcohol sold as rubbing alcohol is generally isopropyl alcohol, which is
turned into acetone by your liver. Some rubbing alcohols may contain
methanol, which is toxic. Even those that are primarily ethanol are
denatured, or rendered undrinkable - often by the addition of poisonous
substances. Methanol is actually one substance commonly added to ethanol to
denature it.
What would happen if you drank rubbing alcohol? From Wikipedia:
Symptoms of isopropyl alcohol poisoning include flushing, headache,
dizziness, CNS depression, nausea, vomiting, anesthesia, and coma. Use in
well-ventilated areas and use protective gloves while using. Poisoning can
occur from ingestion, inhalation, or absorption.
If the rubbing alcohol contains methanol, blindness or death may occur as a
result of its consumption.