A Grandmother was talking to her young grandson, trying to explain the dangers of smoking. "Now Johnny," she said, "you have to promise Grandma that, once you're a grown man, you will never smoke, and never drink."
"Never, Grandma?" asked little Johnny.
"Never, boy, not even once," replied the grandmother.
With his eyes wide as saucers, Johnny asked "But won't I get thirsty?"