Related Clues:

• Sewer resident
• Common test subject
• Muppet Rizzo, e.g.
• Plague carrier
• Dirty dog
• Nocturnal rodent
• Untrustworthy one
• Lab maze runner
• Untrustworthy sort
• It may be down in the dumps
• Snitch (on)
• Renegade
• Nogood-nik
• Pied Piper devotee
• Snitcher