Related Clues:

• "Yeah, whatever!"
• "Nah!"
• Terse negative
• Dubious comment
• 'Not likely!'
• "You're dreaming"
• 'Yeah, as if!'
• "Yeah, as if!"
• Slangy denial, and a hint to 20-, 29-, 46- and 56-Across
• ''Oh, sure''
• "Not a chance"
• 'ÔFraid not'
• "Won't do it"
• ''That'll be the day''
• 'Sure seems like it'