Late for work
Bob had this problem of getting up late in the morning and was always late for work.
After a few weeks of this, his boss was mad and threatened to fire him if he didn't do something about it.
So Bob went to his doctor, who gave him a pill and told him to take it before he went to bed. He got a great night's sleep and actually beat the alarm in the morning. After a leisurely breakfast, he cheerfully drove to work.
"Boss," he said, "The pill my doctor prescribed actually worked!"
"That's all fine," said the boss, "But where were you yesterday"?http://bestsmileys.com/doh/2.gif