Related Clues:

• Sibilant "Hey!"
• Soft "Hey!"
• Sound before 'Your fly's open'
• 'Over here'
• Start of a whispered comment, perhaps
• Subtle 'yo!'
• ''You there!''
• 'Hey . . . over here!'
• Sibilant signal
• Subtle alert
• Relative of ''ahem''
• Furtive ''Yo!''
• Note passer's signal
• Head-turning sound
• Clandestine call