Related Clues:

• Emphatic denial
• Transgression
• Informal denial
• Slangy refusal
• Taboo
• Banned act
• Slangy turndown
• 'Forget it!'
• Faux pas
• It's outlawed
• 'That's a ___!'
• 'No way!'
• Talking during a film, e.g.
• Thou-shalt-not
• Forbidden fruit