Related Clues:

• When pigs fly
• "Nope"
• "Not a chance!"
• "In your dreams!"
• At no time
• 'Don't think so!'
• Opposite of 15-Across
• "Fat chance!"
• Half a fictional land
• "No way!"
• "Don't think so"
• 'Unh-unh'
• "I don't think so!"
• No, informally
• Now alternative