Related Clues:

• Be a stool pigeon
• Tell all, slangily
• Do lullabies, e.g.
• Perform 2-Down
• Join the choir
• Perform with a choir
• When doubled, a New York prison
• Perform on 'American Idol,' e.g.
• Take the mic
• Emulate Justin Bieber
• Rat on the Mob
• Belt one out
• Participate in karaoke
• Perform with the choir
• Join the chorus