Drink Alcohol

A biology teacher wished to strate to his students the harmful
effects of alcohol on living organisms. For his experiment, he showed
them a beaker with pond water in which there was a thriving
civilization of worms. When he added some alcohol into the beaker the
worms doubled-up and died.
"Now," he said," what do you learn from this?"
An eager student gave his answer.
"Well the answer is obvious," he said " if you drink alcohol, you'll
never have worms."