Related Clues:

• "You, over there!"
• 'Watch it!'
• Audible nudge
• Subtler alternative to "Yo!"
• "I'm talking to you!"
• "Do you want to hear a secret?"
• Utterance before passing a note, maybe
• Covert attention-getter
• "What's the big idea?"
• Low-key "Hey!"
• Sibilant "Ahem!"
• "Over here!" sound
• Attention-getting noise
• It's attention-getting
• It may precede "Over here!"