Could Do Better

Teacher - "Didn't you promise to behave?" Johnny - "Yes, sir." Teacher - "And didn't I promise to punish you if you misbehaved?" Johnny - "Yes, sir, but since I broke my promise, you don't have to keep yours." Teacher - "How can one person make so many mistakes in one day?" Johnny - "I get up early." Teacher - "Well, at least there's one thing I can say about your son." Father - "What's that?" Teacher - "With grades like these, he couldn't be cheating."