Related Clues:

• "Ixnay"
• Curt turndown
• "Nope"
• "Not a chance!"
• "Forget about it!"
• "Get out of town!"
• "In your dreams!"
• 'Don't think so!'
• Opposite of 15-Across
• Never!
• "Fat chance!"
• "Impossible!" and the theme of this puzzle
• "No way!"
• "Don't think so"
• 'Unh-unh'