Possible Clues:

• 'I'm not signing that'
• "The agreement is off"
• Game show option after The Banker makes an offer
• "All bets are off!"
• 'Negotiations are off!'
• ''I won't sign!''
• Negotiation's terse conclusion
• Negotiation failure
• Phrase yelled at Howie Mandel thousands of times from 2005 to 2010
• "Nothing doing!"