Possible Clues:

• 'Don't ask' initials
• "Don't interfere," briefly
• 'Butt out!,' briefly
• "Butt out," briefly
• Brief warning to a busybody
• 'Butt out,' briefly
• "Don't be nosy!" shorthand
• "Butt out," for short
• 'Butt out'
• Abrupt ender of a probe