Related Clues:

• 'You dirty --!'
• Stool pigeon
• One who sings
• Wharf pest
• Put -- writing
• Words with rub or pack
• Sewer resident
• Common test subject
• Pack ___ (quit)
• 'Get -- gear!'
• Muppet Rizzo, e.g.
• Plague carrier
• Dirty dog
• Nocturnal rodent
• Untrustworthy one