"Where are you going on vacation, Bob?" Dave asked his co-worker. "Las Vegas." "You don't sound very excited." "Well, I'm a little concerned," said Bob. "Went to Cancun last year, and my wife got pregnant. Went to Hawaii the year before that, and she got pregnant then, too." "Wow! Are you going to take precautions?" "Absolutely. This year I'm taking her with me."