Related Clues:

• 'Holy Toledo!'
• 'Gosh!'
• 'I didn't know that!'
• Cousin of 'hmmm!'
• 'My stars!'
• See 21-Across
• Antiquated euphemism
• 'Oh dear!'
• Cry of mock horror
• 'Oh, no!'
• Word of mock horror
• 'Heavens!'
• Old-time oath
• 'That's incredible!'
• 'No kidding'