Related Clues:

• 'Fat chance'
• "I don't think so"
• Curt turndown
• 'Don't think so!'
• Opposite of 15-Across
• "Don't think so"
• 'Unh-unh'
• "I don't think so!"
• No, informally
• 'Ixnay'
• "Uh-uh!"
• Relaxed rejection
• 'Not a chance'
• Colloquial denial
• No, slangily