Related Clues:

• Sotto voce call
• Subtler alternative to 'Yo!'
• "Hey you!"
• 'Hey, buddy'
• Conversation opener
• Sound from an exam cheater
• "Want to hear a secret?"
• "Stop it!"
• Listen!
• Verbal jab in the ribs
• 'You there!'
• Attention-getting call
• "Hey, Mister!"
• Clandestine signal
• Surreptitious sound