Related Clues:

• 'Nuts!'
• 'Gotcha!'
• 'Yeah, right!'
• 'Phooey!'
• 'I knew it!'
• 'Darn!'
• Cynic's retort
• 'When pigs fly!'
• See 50-Across
• 'That'll show you!'
• 'Forget it!'
• 'I doubt that!'
• 'Yeah, sure!'
• Scrooge's cry
• 'So there!'