Related Clues:

• It may precede 'Don't let anyone hear!'
• "No whispering!"
• Library reminder
• Silencing sound
• "Quiet, please!"
• 'Zip it up!'
• Librarian's reprimand
• 'C'mon, I'm trying to concentrate!'
• ''Keep it down!''
• Admonition on a fishing trip
• Finger-to-lips syllable
• ''Silence!''
• "Be quiet!"
• "Zip your lip!"
• Theater admonishment