"Don't let them hear us!"

• The sound of "Silence!"
• Teacher's admonition
• "Stuff it!"
• Finger-to-lips sound
• "It's a secret!"
• "Be quiet, the movie's starting!"
• "I'm trying to concentrate here!"
• 'Stop talking!'
• "Listen!"

Wiktionary Word definitions in Wiktionary
alt. Requesting silence. Asking people to keep silent. interj. Requesting silence. Asking people to keep silent.