Related Clues:

• Strong denial
• At all, slangily
• ''When donkeys fly!''
• See 19 Across
• "You can't be serious!"
• "Out of the question!"
• 'Impossible!'
• Stern parent's reply
• ''Don't hold your breath!''
• ''You're kidding!''
• On the 31st of February
• 'You're doing it all wrong!'
• ''Not a chance!''
• Not at all, in dialect
• 'No way, no how!'