Possible Clues:

• Words not heard from an 18-Across
• 1-Across's cry
• Shout from a victor
• "Heads ___, tails . . ."
• Gloater's boast
• Counterpart of 'You lose'
• Victorious declaration
• Uncommon cry after a lottery drawing
• Victorious words
• Gleeful cry after a coin flip