FINK

Act the rat

• Barton ___

• Automatic teller?

• Be a snitch

• Bean spiller

• Betrayer

• Betrayer of confidences

• Canary, so to speak

• Disloyal sort

• He rats people out to the fuzz

• Informer

• Obnoxious sort

• Rat

• Rat on

• Singer?

• Snitch

• Soprano canary

• Squealer

• Stool pigeon

• Stoolie

• Strikebreaker

• Whistle-blower

• Someone acting as an informer or decoy for the police