Related Clues:
- Covert sound
- Signal from a man in a trenchcoat
- Subtle ''Hey you!''
- Low-key ''Hey!''
- Sibilant attention-getter
- '___! Pass it on ... '
- Sibilant Hey!
- ''Wanna hear a secret?''
- Quiet 'Hey!'
- Muffled ''Hey, you!''
- Discreet call
- Verbal elbow
- Surreptitious attention-getter
- Call to attention?
- Subdued attention-getter