Related Clues:

• Wharf pest
• Blab freely
• Hootenanny, e.g.
• Sewer resident
• Common test subject
• Let the air out?
• Muppet Rizzo, e.g.
• Plague carrier
• Dirty dog
• Nocturnal rodent
• Untrustworthy one
• Belt, perhaps
• Lab maze runner
• Untrustworthy sort
• It may be down in the dumps